Non-slip transmissions particularly useful as continuously-variable transmissions and transmission members thereof

ABSTRACT

A continuously-variable transmission includes two transmission members each having coupling elements engageable to couple the transmission members for movement together. At least one of the transmission members is a rotary member rotatable about a rotary axis; and at least one of the groups of coupling elements is radially displaceable towards and away from the rotary axis to change the conversion ratio of the transmission. The coupling elements of one group on one transmission member are of a fixed configuration defining projections alternating with depressions each of a fixed configuration formed on a surface of the transmission member between opposite side faces and having the same pitch for every cross section of the surface perpendicular to the mentioned rotary axis. The coupling elements of the other group are of a self-adaptive configuration, each movable in opposite directions to adapt itself to the configuration of the fixed-configuration coupling elements in all displacement positions of the radially-displaceable coupling elements and to effect a non-slip coupling therewith.

FIELD AND BACKGROUND OF THE INVENTION

[0001] The present invention relates to non-slip transmissionsparticularly useful as continuously-variable transmissions, and also totransmission members included therein.

[0002] A main problem in many types of existing continuously-variabletransmissions (CVTs) is slippage between the contacted surfaces.Slippage causes rapid wear of the contact surfaces, together with energylosses and low efficiency. These problems become more serious as thetransmitted torque increases. For this reason, continuously-variabletransmissions currently find little use in machines requiring hightorque transmission, such as medium and heavy vehicles and industrialmachinery.

[0003] The continuously-variable transmissions used at present aregenerally based on high-pressure contact between two smooth surfaceshaving a high coefficient of friction, rather than on contact betweenmetallic bodies such as gear wheels which cannot slip and which have alow coefficient of friction. The commonest examples of thepresently-used systems are those based on a V-belt made of rubber. Thehigh coefficient of friction and the high pressure between the surfacesare intended to prevent slippage, but even this is insufficient incertain cases. Such systems may be adequate for the transmission ofsmall torques, but are generally considered to be uneconomical andinefficient when applied to the transmission of high torques.

[0004] Transmission systems based on gears include a driving member anda driven member, engaging each other by matching sets of projections anddepressions (gear teeth) that force one member to move along with theother member without slippage. The transmission ratio between thedriving member and the driven member in these gears is constant.

[0005] As the transmission ratio of such gears is determined by theratio between the number of cogs or teeth (projections) on each member,they cannot be used for producing a variable transmission ratio: If thediameter of one member is changed without changing the number of teeth,then the pitch between the teeth will not match the other member; and ifthe diameter is changed while preserving the pitch, then the number ofteeth around the member will, at times, be fractional—making itimpossible to continuously engage with the other member.

[0006] Several patents have issued on methods to create a non-slipcontinuously variable transmission (CVT), including the following:

[0007] U.S. Pat. No. 1,650,449 (Jaeger) and U.S. Pat. No. 4,952,196(Chilcote) disclose a CVT in which two wheels change their overalldiameters so that a fixed length chain is suspended around both. Formany wheel diameters in this method, the circumference of the wheel isnot an integer number of teeth; therefore, a link of the chain will meetthe circumference of the wheel out of phase. Special cumbersome meansare therefore necessary to overcome this problem, if possible at all.

[0008] U.S. Pat. No. 1,601,662 (Abbott) discloses a CVT that addressesthe above problems by a conical structure in which coupling elements inone member adjust their position to match the topography of the othermember in each and every diameter. This method requires the couplingelements to converge to their operational position through a cumbersomeback and forth trajectory in which they slide on and collide with otherparts of the topography in a non-matching angles of contact, creatingincreasing friction and bending moments.

[0009] U.S. Pat. No. 6,055,880 (Gogovitza) discloses another conicalapproach of a CVT that ensures positive engagement at any transmissionratio, and addresses the problem of U.S. Pat. No. 1,601,662 by bringingeach coupling element directly to its operational position. However, theconical structure of the system of this patent creates a non-uniformpitch and a non-uniform speed along the line of contact between thecoupling element and the topography, resulting in the creation of unduedifferential stresses, bending moments, and slippage between the coupledelements. In practice, this system implies a small number of small linesof contact—thus a limited transmission of moments.

OBJECTS AND BRIEF SUMMARY OF THE INVENTION

[0010] An object of the present invention is to provide a transmission,and particularly a continuously-variable transmission (CVT), havingadvantages in some or all of the above respects. More particularly, anobject of the invention is to provide a continuously-variabletransmission which is capable of driving large loads, whichsubstantially eliminates slippage, which provides a sufficient area ofcontact between the engaged surfaces, and/or, which is characterized bylow friction losses and high durability. Another object the invention isto provide a CVT having the capability of an infinitely-variabletransmission (IVT). A further object is to provide a novel transmissionmembers particularly useful in such transmission systems.

[0011] According to one broad aspect of the present invention, there isprovided a continuously-variable transmission, comprising: first andsecond transmission members each having a group of coupling elementssuccessively engageable to couple the transmission members for movementtogether; at least one of said transmission members being a rotarymember rotatable about a rotary axis; at least one of said groups ofcoupling elements being radially displaceable towards and away from therotary axis to change the conversion ratio of said transmission; thecoupling elements of one of said groups on one of said transmissionmembers being of a fixed configuration defining an array of projectionseach of a fixed configuration alternating with depressions each of afixed configuration; said array of projections and depressions being ona surface of said one transmission member between opposite side faces ofsaid one transmission member, and having the same pitch for everycross-section of said surface perpendicular to the rotary axis; thecoupling elements of the other of said groups on the other of saidtransmission members being of a self-adaptive configuration, eachindividually movable in opposite directions to adapt itself to theconfiguration of said fixed configuration coupling elements in alldisplacement positions of the radially displaceable coupling elementsand to effect a non-slip coupling therewith in all said radialdisplacement positions.

[0012] A “pitch” of an array of projections and depressions is thedistance between common points on the array. In the CVT of the presentapplication, the pitch of the surface formed with the projections anddepressions is the same for every cross-section of the surfaceperpendicular to the rotary axis; this distinguishes from the conicalsurfaces of many of the prior-art CVT systems, and thereby, avoids manyof the drawbacks of the prior art systems as briefly described above.

[0013] According to further features in the preferred embodiments of theinvention described below, the projections and depressions of thefixed-configuration coupling elements at one side face of the onetransmission member are in a staggered relationship with respect to theprojections and depressions at the opposite side face of the onetransmission member, such that each projection in one side face isaligned with a depression in the opposite side face, along a lineparallel to the rotary axis.

[0014] In some preferred embodiments described below, each of thefixed-configuration coupling elements includes a gradual transition froma projection at one side face to a depression at the opposite side andin other described preferred embodiments, each of thefixed-configuration coupling elements includes a stepped transition froma projection ate one side face to a depression at the opposite sideface.

[0015] As will be described more particularly below, the foregoingfeatures enable continuously-variable transmissions to be providedhaving no significant slippage or friction despite the variations inspacing of the coupling elements produced with the variations indiameters of the respective transmission member. The foregoing featuresfurther provide a large area of contact between the coupling elements,minimal energy losses, and a capability of high torque transfer. Inaddition, such systems avoid the creation of undue differential stressesin the coupling elements along the contact lines, characteristic ofcontinuously-variable transmission (CVT) systems having projections anddepressions on conical surfaces. Such a transmission is also capable ofbeing designed as an infinitely-variable transmission (IVT) having alarge range of possible transmission ratios, even down to a zerovelocity on the output shaft without the need for a clutch.

[0016] More particularly, and as will be described more particularlybelow, the present invention overcomes the drawbacks of the abovedescribed prior art CVT systems by providing self adaptable elementsthat:

[0017] 1. adjust themselves without friction to the topography at anytransmission ratio,

[0018] 2. adjust themselves without friction to the topography at anyincidental point of contact,

[0019] 3. adjust themselves by moving in the direction of engagementbetween the members—as ordinary cog wheels are engaging into each other,

[0020] 4. maintain a uniform pitch across the contact line with thetopography, thus ensuring equal speed of motion and equal pressurebetween the members,

[0021] 5. are capable of being designed with any desirable length of theline of contact, to enable high forces and high transmission moment.

[0022] In addition, the CVT mechanism of this invention can be designedin a large variety of configurations, including parallel input andoutput axii, concentric input and output members, indirect (e.g., chain,belt), and direct transmission.

[0023] A large number of embodiments of the invention are describedbelow for purposes of example. In some described embodiments, the rotarymember is a variable-diameter toothed wheel carrying the self-adaptivecoupling elements in a radially-displaceable manner thereon; and theother transmission member is a fixed-diameter toothed wheel, or atoothed rack, or a flexible chain or belt, which carries thefixed-configuration coupling elements. Other embodiments are describedwherein the other transmission member carries the self-adaptive couplingelements in a radially-displaceable manner; and the rotary membercarries the fixed-configuration coupling elements. In some of the latterdescribed embodiments, the other transmission member includes a discformed with an annular array of radial slots around a central axis; andthe self-adaptive coupling elements include an annular array of pinsdisplaceable within the slots towards and away from the central axis.

[0024] Still further embodiments are described wherein the rotary membercarries the fixed-configuration coupling elements in aradially-displaceable manner; and the other transmission member carriesthe self-adaptive coupling elements in an individually displaceablemanner to adapt themselves to the configuration of thefixed-configuration coupling elements in all displacement positionsthereof.

[0025] According to another aspect of the present invention, there isprovided continuously-variable transmission, comprising: first andsecond transmission members each having a group of coupling elementssuccessively engageable to couple the transmission members for movementtogether; at least one of said transmission members being a rotarymember rotatable about a rotary axis; at least one of said groups ofcoupling elements being radially displaceable towards and away from therotary axis to change the conversion ratio of said transmission; thecoupling elements of one of said groups being of a fixed configurationdefining projections alternating with depressions each of a fixedconfiguration; the coupling elements of the other of said groups beingof a self-adaptive configuration, each individually movable in oppositedirections to adapt itself to the configuration of said fixedconfiguration coupling elemenrs, in all displacement positions of theradially displaceable coupling elements; said other transmission memberincluding a disc formed with an annular array of radial slots; saidself-adaptive coupling elements including an annular array of pinsdisplaceable within said slots; and said rotary member including a gearassembly having a gear meshing with said annular array of pins forproducing a non-slip coupling therewith while effecting relativerotation between said disc and said gear assembly about the center ofsaid annular array.

[0026] The term “toothed wheel” is used herein in its broadest sense toinclude any type of rotary transmission member having projections anddepressions coupled to projections and depressions of anothertransmission member to transfer torque from one to the other. Thus, thetoothed wheel may be of relatively small axial dimension, such as in atoothed gear or toothed disc, or of relatively large axial dimension,such as in a toothed cylinder or drum.

[0027] According to another aspect of the invention, there is provided atransmission system including a continuously-variable transmissionhaving one or more of the foregoing combination of features, a conditionsensor for sensing a predetermined condition, and an automatic controlsystem for automatically displacing the first group of projections anddepressions to change the effective diameter of the rotary member, andthereby the transmission ratio of the continuously-variabletransmission, in response to the sensed condition.

[0028] In one described preferred embodiment, the condition sensorsenses velocity of the transmission or the drive thereof (e.g., velocityof the foot pedals in a bicycle) and automatically controls thetransmission ratio in response thereto; and in another describedembodiment, the condition sensor senses load on the transmission or thedrive thereof (e.g., load on the engine in a motorized vehicle) andautomatically controls the transmission ratio in response thereto. Theautomatic control system may further include a response selector forselecting one of at least two predetermined responses, (e.g., slow orfast) of the automatic control of the transmission ratio to thepredetermined sensed condition.

[0029] According to yet another aspect of the present invention, thereis provided a variable-diameter rotary wheel particularly useful in sucha continuously-variable transmission, comprising: an inner pair ofspaced discs joined together by a first ring, and an outer pair ofspaced discs joined together by a second ring coaxial with the firstring; one pair of discs being formed with a plurality ofradially-extending straight slots, and the other pair of discs beingformed with a plurality of radially-extending curved slots; and aplurality of pins having their opposite ends received in both a straightslot and in a curved slot of the respective discs, such that rotation ofone of the discs in each pair with respect to the other disc in the paircauses the pins to move radially with respect to the discs, according tothe direction of rotation, thereby changing the effective diameter ofthe rotary member.

[0030] According to a still further aspect of the invention, there isprovided a continuously-variable transmission, comprising: first andsecond transmission members each having a group of coupling elementssuccessively engageable to couple the transmission members for movementtogether; at least one of said transmission members being a rotarymember rotatable about a rotary axis; at least one of said groups ofcoupling elements being radially displaceable towards and away from therotary axis to change the conversion ratio of said transmission; thecoupling elements of one of said groups being of a fixed configurationdefining projections alternating with depressions each of a fixedconfiguration; the coupling elements of the other of said groups beingof a self-adaptive configuration, each individually movable in oppositedirections to adapt itself to the configuration of said fixedconfiguration coupling elements in all displacement positions of theradially-displaceable coupling elements; said rotary member including aninner pair of spaced discs joined together by a first ring, and an outerpair of spaced discs joined together by a second ring coaxial with saidfirst ring; one pair of discs being formed with a plurality ofradially-extending straight slots, and the other pair of discs beingformed with a plurality of radially-extending curved slots; the oppositeends of each of said of coupling elements of said rotary member beingreceived in both a straight slot and in a curved slot of the respectivediscs such that rotation of one of said discs in each pair with respectto the other disc in the pair causes said coupling elements to moveradially with respect to said discs, according to the direction ofrotation, thereby changing the effective diameter of the rotary member.

[0031] According to further aspects of the invention, there are providedother variable-diameter rotary wheel constructions particularly usefulin the continuously-variable transmission of the present invention.

[0032] According to another aspect of the present invention there isprovided a transmission for transmitting mechanical motion in apredetermined direction between a first member and a second member; thefirst member including a coupling element; the second member having anengagement surface formed with a topography of projections anddepressions in a periodic pattern of the same pitch in everycross-section parallel to the direction of motion; the coupling elementof the first member being placeable on the engagement surface of thesecond member at any point along the direction of motion and resting onthe surface along at least one line of contact defined by points ofrest; the coupling element of the first member having at least one pointthat does not change its elevation above the second member for any ofthe points of rest; the line of contact resting at least partially on apositive slope and partially on a negative slope of the engagementsurface.

[0033] According to further features in this aspect of the invention,the first member is a variable diameter rotary member including anannular array of the coupling elements radially displaceable to changeits effective diameter, and thereby to enable the transmission tocontinuously-vary the transmission ratio between the first and secondmembers.

[0034] According to yet another aspect, the invention provides atransmission for transmitting mechanical motion between a rotary drivingmember and a rotary driven member having parallel axes of rotation,comprising: a pin parallel to the axes of rotation of said driving anddriven members; one of said members being engageable with said pinallowing it a relative movement only in a direction that is essentiallyperpendicular to said axes of rotation and perpendicular to the pin; theother of said members being engageable with said pin such that when saidother member is rotated, it forces the pin to move in both thetangential and the radial directions, wherein the tangential movement isin the direction of said motion, and the radial movement is periodicaround a median radius.

[0035] According to yet another aspect of the invention, there isprovided a transmission member for coupling to a rotary member rotatableabout a rotary axis; the transmission member having opposite side facesand a surface between the side faces formed with an array of projectionsand depressions for coupling to another transmission member; the arrayof projections and depressions being of the same pitch from one sideface to the opposite side face; the projections and depressions in oneside face being in a staggered relation to the projections anddepressions in the opposite side face, such that each projection in oneside face is aligned with a depression in the opposite side face along aline parallel to the rotary axis. Various embodiments are describedwherein the transmission member is a toothed wheel, a closed-loopflexible chain, a closed-loop flexible belt, and a rack.

[0036] Further features and advantages of the invention will be apparentfrom the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

[0038] In the drawings:

[0039]FIG. 1 illustrates one form of continuously-variable transmission(CVT) constructed in accordance with the present invention;

[0040]FIG. 2 more particularly illustrates the variable-diameter toothedwheel in the transmission of FIG. 1;

[0041]FIG. 3 illustrates one of the self-adaptive coupling elements inthe transmission of FIG. 1;

[0042]FIG. 4 illustrates the fixed-diameter toothed wheel in thecontinuously-variable transmission of FIG. 1;

[0043]FIG. 5 illustrates a modification in the construction of theself-adaptive coupling element of FIG. 3;

[0044]FIG. 6 illustrates a CVT including another type of fixed-diametertoothed wheel;

[0045]FIG. 7 more particularly illustrates the fixed-diameter toothedwheel of FIG. 6;

[0046]FIGS. 8 and 9 illustrate self-adaptive coupling elements that maybe used with the toothed wheel of FIGS. 6 and 7;

[0047]FIGS. 10 and 11 illustrate further examples of construction of theself-adaptive coupling elements and the fixed-configuration couplingelements, respectively;

[0048]FIG. 12 illustrates a CVT constructed in accordance with thepresent invention, similar to that of FIG. 1, but including a toothedrack rather than a toothed wheel;

[0049]FIG. 13 illustrates a CVT constructed in accordance with thepresent invention utilizing a closed-loop chain;

[0050]FIG. 14 illustrates a transmission similar to that of FIG. 13 butincluding two variable-diameter toothed wheels coupled by the closedloop chain;

[0051]FIGS. 15-18 illustrate a construction of chains which may be usedin the transmission of FIG. 13 or FIG. 14 with variable-diameter toothedwheels including self-adaptive coupling elements of the type illustratedin FIG. 8;

[0052]FIG. 19 illustrates an alternative chain construction that may beused with variable-diameter toothed wheels including self-adaptivecoupling elements of the type illustrated in FIGS. 1-5;

[0053]FIGS. 20 and 21 illustrate two constructions of a closed loop beltwhich may be used in a transmission similar to that of FIGS. 13 or 14having self-adaptive coupling elements of the type of FIGS. 3 and 8,respectively;

[0054]FIG. 22 illustrates another construction of chain, together withanother construction of self-adaptive coupling element, which may beused in such a transmission;

[0055]FIGS. 23 and 24 illustrate another construction of chain and aself-adaptive coupling element, respectively, which may be used in thetransmission of FIGS. 13 or 14;

[0056]FIGS. 25 and 26 schematically illustrate two further constructionsof self-adaptive coupling elements which may be used;

[0057]FIGS. 27 and 28 illustrate a toothed wheel and a self-adaptivecoupling element, respectively, for use in a transmission such asillustrated in FIG. 1 but each provided with resilient pads to cushionthe contact with their respective coupling elements;

[0058]FIG. 29 illustrates another construction of variable-diametertoothed wheel (without the coupling elements) in accordance with theinvention;

[0059]FIG. 30 illustrates a self-adaptive coupling element for use withthe toothed wheel of FIG. 29;

[0060]FIGS. 31, 32 and 33 illustrate three further variable-diametertoothed wheel constructions in accordance with the present invention;

[0061]FIG. 34 is an exploded view, and FIG. 35 is an end view,illustrating a further variable-diameter toothed wheel construction inaccordance with the present invention;

[0062]FIG. 36 is a perspective view of a CVT including a chain and thevariable-diameter toothed wheel of FIGS. 34 and 35;

[0063]FIG. 37 illustrates an example of one of the radially-displaceablecoupling elements in the variable-diameter toothed wheel of FIGS. 34-36;

[0064]FIGS. 38 and 39 illustrate two CVT systems, each according toFIGS. 34-37 and each having an automatic control for controlling thetransmission ratio in response to velocity or other predeterminedcondition, such as load;

[0065]FIGS. 40 and 41 illustrate CVT systems, similar to those of FIGS.2, 29, 31 or 32, including other arrangements for-automatic control ofthe transmission ratios;

[0066]FIG. 42 illustrates a CVT system of the type illustrated in FIGS.34-37 equipped with a differential mechanism enabling continuous controlwhile the transmission is rotating;

[0067]FIG. 43 illustrates a CVT system of the type illustrated in FIGS.34-37 equipped with a differential mechanism to enable the system tooperate as an infinitely-variable transmission (IVT) with zero velocityat the output shaft;

[0068]FIGS. 44-46 illustrate a CVT system including one manner ofincreasing the range of transmission ratios and/or load capabilities;

[0069]FIG. 47 illustrates an implementation of the invention in a CVTsystem in which one of the transmission member includes avariable-diameter toothed wheel having an annular array of pin couplingelements serving as a rotating or non-rotating ring gear, and the othertransmission member is a gear assembly having gears located on oppositesides of the pins and meshing with them;

[0070]FIG. 48 illustrates one of the pin coupling elements in thetransmission of FIG. 47;

[0071]FIG. 49 is an end view of the CVT system of FIG. 47;

[0072]FIGS. 50 and 51 illustrate two further implementations of theinvention in CVT systems including toothed wheels havingvariable-diameter pin arrays;

[0073]FIGS. 52-55 illustrate a further implementation of the inventionin a CVT system including a variable-diameter toothed wheel having anannular array of pins;

[0074]FIG. 56 illustrates another CVT system in accordance with theinvention, wherein one of the transmission members is a fixed-diametertoothed wheel having an annular array of the self-adaptive pin couplingelements, and the other transmission member is a variable-diametertoothed wheel having the fixed-configuration coupling elements;

[0075]FIG. 57 illustrates a CVT system similar to that of FIG. 56 butincluding a chain having the self-adaptive coupling elements couplingtwo variable-diameter toothed wheels having the fixed-configurationcoupling elements;

[0076]FIG. 58 illustrates a CVT system including two rotary members oflike construction, each pivoted with the self-adaptive coupling elementsand the fixed-configuration coupling elements, the two rotary membersbeing coupled together to provide a continuously-variable transmission;

[0077]FIGS. 59a and 59 b schematically illustrate two stages of anotherCVT system constructed in accordance with the present invention toprovide an infinitely-variable transmission (IVT) capability;

[0078]FIG. 60 is an end view of the CVT system of FIGS. 59a and 59 b;

[0079]FIG. 61 is an exploded view of the CVT system of FIG. 60 includinga planetary gear assembly for multiplying the range of transmissionratios permissible by the transmission;

[0080]FIG. 62 illustrates one of the pins in the annular pin array inFIG. 61;

[0081]FIG. 63 illustrates another CVT system constructed in accordancewith the present invention similar to that of FIGS. 60-62 but modifiedsuch that the radially-displaceable annular array of pins defines aninterior gear rather than an exterior gear; and

[0082]FIG. 64 illustrates a CVT system similar to that of FIG. 63, butincluding a control mechanism for manually or automatically controllingthe conversion ratio.

MECHANISM OF ACTION

[0083] The present invention discloses a mechanism for continuousvariable transmission which serves for continuously varying thetransmission ratio between an input (driving) transmission member and anoutput (driven) transmission member, using mechanical engagement betweenthe two transmission members. The engagement between the transmissionmembers is mediated by coupling elements that are forced to move in thedriving direction by the driving member, and in turn force the drivenmember to move in the same direction.

[0084] An important feature of the present invention is in the way bywhich the coupling elements are connected to one of transmissionmembers, and in the way that they are coupled to the surface of theirmember. This innovative way enables the transmission of the presentinvention to change the transmission ratio between the members withsubstantially no slippage and minimal friction.

[0085] In all embodiments of the invention described below, at least oneof the two members is rotary, rotating around an axis. This member isequipped with an annular arrangement of coupling elements, havingprojections and depressions designed to match depressions andprojections in the other transmission member, and with a mechanism ofchanging the effective radius of the annular arrangement. Changing theradius of the annular arrangement changes the effective radius of thetransmission member and therefore changes the transmission ratio of thetransmission, but at the same time it also changes the tangentialdensity of the coupling elements, and therefore makes it impossible toengage the coupling elements into an ordinary transmission member suchas a cog wheel or a transmission chain or belt. These ordinarytransmission elements have a constant pitch, thus cannot be engagedwithout slippage or friction with an annular arrangement of elementshaving a varying pitch.

[0086] In the embodiments of the invention described below, the couplingelements on the rotational transmission member change their pitch, as aresult of changing the annular arrangement radius. These couplingelements, or the coupling elements that define the topography of theother transmission member, have a degree of freedom for local movement(rocking, rotation or small displacement) that enables these couplingelements, upon approaching contact with the topography of the othertransmission member, to adapt themselves to the topography of the othermember, so that, upon tight contact, they will contact each other alongat list one line of contact (rest points), without extracting a momenton each other in the direction of transmission. This feature can beachieved in any one of several ways some of which are described infurther detail hereinbelow. In some described embodiments (e.g., FIGS.1-4, as well as some of the others) this is achieved by allowing thecoupling elements of one of the members to move about, e.g., around apivot point, and self-adapt into contact with the topography of theother member, so that at least portions of the contact line contact thetopography of the other member against a positive slope, hence forcingthe other member to move in the transmission direction. The transmissiontakes place where the pivot point of the coupling element is driven byone of the members, and the driven member is moved through the motion ofthe line of contact with the other member is due to the positive slopeof the topography. The geometry of the coupling member is such that thepositive contact with the other member takes place while the pivot pointdoes not change its radius.

[0087] The line of contact between the coupling elements and the othermember is oriented so that the pitch of the topography is essentiallyconstant across the line of contact, so that when motion takes place,there is negligible slippage or friction between the coupling elementsand the other member. Moreover, the geometry can be designed usingevolving shape, making the transmission mechanism similar to an ordinarycogwheel.

[0088] In order to explain the mechanism that maintains the contactbetween the coupling element and the surface of the other member withoutslippage, the transmission member that is connected to the couplingelement will be referred to in the following paragraphs as “the drivingmember” and the transmission element that is brought in contact with thecoupling element “the driven member”. It will however be appreciatedthat the roles (“driving” and “driven”) of the members can be reversed.

[0089] Thus, in the FIGS. 1-4 embodiment, the driving member holds thecoupling elements so that, for a given transmission ratio, the distanceof the pivot of the coupling elements from the rotation axis of thetransmission member is constant. The pivot of the coupling element caneither be a physical axis that is connected to the driving member, or avirtual pivot that is defined by a circular guide in which the couplingmember can rotate. The driving member is holding all the couplingelements at their pivot, rotating them as it moves, and pushing themtowards the surface (topography) of the driven member. As the couplingelement is approaching the surface of the driven member, one of itsprojected edges will touch the surface, and as the coupling element isfree to move about its pivot, the coupling element will adapt itposition to give way to the approaching surface. The movement willcontinue until another point of the coupling element will contact thesurface of the driven member, and at that moment the coupling elementwill be supported by at least three points, and will be constrained fromany further movement relative to its pivot. Further force of the drivingmember towards the driven member will increase the pressure between thetwo members (through the mediation of the coupling element).

[0090] This situation could now cause the coupling member to slip orslide on the surface of the driven member in an attempt to give way tothe driving member to come even closer to the driven member. However,the specific topography of the surface of the driven member and thegeometry of the coupling element do not allow this slippage: Thetopography of the driven member is such that for any relative positionof the coupling element relative to the surface of the driven element,the sum of displacements of both ends of the contact line between themis constant. This means that if one edge of the coupling element has tobe recessed by 2 mm in order to touch the surface of the driven member,then the other edge of the same coupling element has do be projected by2 mm in order to touch the surface of the driven member. Such topographycan easily be created by designing the driven member as a pair of twoparallel disks with a varying radii. The first disk can have, forexample, 36 sinusoidal periods along its perimeter following theequation R(φ°)=12 cm+sin(10*φ°), while the other disk can have 36sinusoidal projections and depressions following the equation R(φ°)=12cm−sin(10*φ°). It is clear that for any angle φ, a segment that connectsthe respective point of angle φ on the two disk perimeters, will haveits center on an imaginary circle between the two disks, with a fixedradius of 12 cm. Thus, if this imaginary circle contains the pivotpoints of the annular arrangement of coupling elements, and if thestraight segment represents the contact line of the coupling elementswith the topography of the driven member, and further if the two disksrepresent the topography of the driven member, then for any contactingposition, (and after due consideration of the size and shape of thecoupling elements), the projection of one edge of the coupling elementis identical to the recession of the other end, and the pivot pointpreserves its distance from the rotation axis.

[0091] It is clear that there are many other topographies that satisfythis requirement, other than that of FIGS. 1-4, and that the topographycan be continuous and touch the coupling element along a line or aplurality of lines while maintaining a similar condition as in FIGS.1-4.

[0092] As the topography of the driven member has positive and negativeslopes, it is clear that when the coupling member is pressed onto italong the line of contact, and is also pushed in the driving direction,one of the edges of the coupling element will be engaged with the slopeof the driven member so as to force it to move along in the direction oftransmission. If the coupling element is contacting the driven memberalong a line, than part of the contact line will meet the topography ofthe driven member in a positive slope and the mechanical engagement willtake place along that half line.

[0093] The slopes of the topography should, at least at some places, besufficiently steep to prevent the coupling element from sliding alongthe curves of the topography.

[0094] It is to be noted that the small movement that the couplingelement has to move while approaching the driven member towards itssettled position, takes place at the direction of coupling, so that theforce needed to be applied on the coupling element to bring it to itssettled position is negligible and is easily provided by the drivingmember.

[0095] It is also to be noted that the movement that the couplingelement has to move while approaching the driven member towards itssettled position is small and unidirectional.

[0096] The length of the line of contact can be designed to be longenough to support high driving forces. Such a length can be provided byenlarging the width of the driven member. It will be appreciated that itdoes not imply an increase of the diameter of the transmission.

[0097] The continuous transmission described herein can be implementedin a wide variety of mechanisms in addition to that of FIGS. 1-4. It canbe designed so that the effective diameter of the driving member will bechanged by changing the distance between two disks, and the two diskscan partially overlap each other along the axis of rotation, thus savingspace and enabling relatively small mechanisms.

[0098] The driven member can be a chain, rather then a wheel. The twoparallel faces of the link of the chain will be cut to have the desiredtopography, and the coupling element that will, in this case, byconnected to the driving wheel, will adapt themselves to meet the linkalong lines that are parallel to the joint connecting the links to eachother. By using the faces of the link to perform the contact with thecoupling element, the axii of the links are free to be engaged with anordinary cogwheel, enabling the chain to be driven by the CVT of thisinvention, and in turn drive an ordinary cogwheel.

[0099] The CVT described herein can be applied to an infinite variabletransmission (IVT) mechanism, that can change the transmission ratiobetween the driving and driven members from any negative ratio to anypositive ratio through the zero value (in which the driven member willnot be rotating at all while the driving member is rotating). This canbe done by holding a differential cogwheel between two parallel cogdisks with their annular arrangement of cogs facing each other andengaged to the differential cogwheel. By engaging one of the parallelcog disks to the driving member so that its rotation speed is determinedby some fixed transmission ratio, and engaging the other cog disk to aCVT mechanism as described herein, giving it a range of speeds thatchanges from slower than the first cog disk to higher than the cog disk,the differential cog wheel will rotate around itself at a rate that isproportional to the difference between the speeds of the two cog disks,and will revolve around the axis of the cog disks at a rate that isproportional to the sum of the speeds of the two cog disks. As this sumcan be negative, zero or positive, the differential will revolve at aninfinite transmission ratio.

[0100] There are several ways to control the effective radius of thering of coupling elements, thus changing the transmission ratio of thetransmission. Examples of these methods are described in detail herein.

[0101] One method is to hold the coupling elements on sliding membersthat can change its radial position, apply to it a permanent force(typically using a spring) towards one direction (either inwards oroutwards), and apply a positive controllable force in the oppositedirection to overcome the permanent force and bring the pivot of thecoupling member to the desired radius.

[0102] A second method is to hold the coupling elements in guides thatallow the elements to move radially towards and away from the axis ofrotation of the driving member, to capture the coupling element betweenthe driven member and a support wheel on the driven member that keeps itengaged to the driven member, and changing the distance between the axiiof the two members so that the coupling element will be forced to changeits position along the guides of the driving member and hence change theeffective radius of the transmission.

[0103] A third method is to hold the coupling elements between two pairsof parallel disks, one pair having facing parallel slots through whichthe coupling member is threaded, and the other pair having the samenumber of facing spiral slots through which the same coupling element isalso threaded. Each radial slot has an overlap with one spiral slot sothat there is one straight through passage through the four disks, andthe coupling element is forced to be positioned at this point ofoverlap. By changing the angular position of the radial slots inrelationship to the spiral slots, the point of overlap changes itsradius, forcing the coupling elements to change their radius and hencethe ratio of transmission.

[0104] An important feature of this invention, therefore, is the use ofa coupling element that has a limited freedom to move about its holdingtransmission member around a line, that will be defined and referred tobelow as “the coupline”.

[0105] The coupling elements in the embodiments of this invention areself-adaptive, in the sense that when they come into proximity with thetopography of the other transmission member in the course of thetransmission process, they change their spatial orientation.

[0106] Before the self-adaptation begins, the orientation of thecoupling element is determined by the way it is connected to the firsttransmission member. This way of connecting may allow the couplingmember some limited free motion, and forces, such as gravitation,centrifugal force, and spring action, may effect its orientation withinthat limited free motion.

[0107] After the self-adaptation terminates, the orientation of thecoupling element is firmly constrained between the transmission elementsand is essentially stationary in relation to both members, until it endsits “duty” to deliver the moment from the first transmission member tothe second transmission member, whereupon it is released from betweenthe members to resume its limited freedom position, until it will becalled to “duty” again.

[0108] For each of the coupling members, there is a line, parallel tothe axis of rotation of the rotary transmission member, that crosses thetransmission member to which the coupling element is connected at afixed point, that has the same distance from the second transmissionmember at the end of the adaptation process, for any possible positionof contact between the coupling element and the transmission member. Insome embodiments of the invention described below, this line is thecenter of an axis that holds the coupling member on the transmissionmember. In other described embodiments, this line is the center of acircular groove in the transmission member, inside which the disk-shapedcoupling member can rotate. In yet other embodiments this line is themedian of a plurality of possible locations of a pin that moves withinthe coupling elements.

[0109] The fact that this line, hereinafter called “the coupline”, isfixed regarding the holding transmission member, ensures that thecoupling element will be firmly engaged with the second transmissionmember for any transmission ratio and for any point of contact along thetopography.

[0110] The existence of the coupline is an important feature of thisinvention and clearly distinguishes it from prior CVT systems. Itenables the two transmission members to be in a positive mechanicalengagement with each other, as in an ordinary spur gear transmission,while the phase of engagement between them is completely continuous andcan take place at any phase they meet—like in a friction belt gear.Another advantage of the CVT of the present invention is that it permitsthe axes of the drive and driven shafts to be parallel to each other, asin a spur gearing system.

GENERAL CONSTRUCTION AND ADVANTAGES OF DESCRIBED EMBODIMENTS

[0111] The continuously-variable transmission of the present inventionis described below with respect to a large number of preferredembodiments all of which include a combination of features producing anumber of important advantages, as will also be described moreparticularly below.

[0112] One feature common to the described embodiments is that at leastone of the two transmission members is a rotary member rotatable about arotary axis. In most of the preferred embodiments described below, therotary member is a toothed wheel (as broadly defined above); and theother transmission member is also a rotary member, e.g., another toothedwheel, a flexible closed-loop chain or belt, etc. However, otherembodiments are described wherein the other transmission member isnon-rotary, e.g., a linearly-movable rack, or a ring gear which may befixed or rotatable.

[0113] According to further features common to the preferred embodimentsof the invention described below, at least one of the groups of couplingelements is radially displaceable, preferably as a group, towards andaway from the rotary axis to change the conversion ratio of thetransmission. According to still further common features, the couplingelements of one of the groups on one of the transmission members is of afixed configuration defining projections alternating with depressionseach of a fixed configuration. As described below, the array ofprojections and depressions formed on a surface of the one transmissionmember extending between opposite faces of that transmission member, andhave the same pitch from one side face to the opposite side face. Inaddition, the coupling elements of the other group on the othertransmission member is of a self-adaptive configuration; that is, eachis individually displaceable to engage oppositely sloped surfaces of thearray of projections and depressions, and thereby adapting themselves tothe configuration of the fixed-configuration coupling elements in alldisplacement positions of the radially-displaceable coupling elements toeffect a non-slip coupling therewith in all the radial displacementpositions.

[0114] The radially-displaceable coupling elements may be on eithertransmission member. In addition, the fixed-configuration couplingelements may be on either transmission member, and the self-adaptivecoupling elements may be on the other transmission member. Hence, itwill be appreciated in this respect that either the fixed configurationprojections and depressions or the self adaptive projections anddepressions can be those coupling elements that are radiallydisplaceable so as to control the transmission ratio.

[0115] Since the pitch of the projections and depressions, i.e., thedistance between common points thereon, is the same on both side facesof the transmission member, the creation of differential stresses alongthe contact lines between the transmission members, characteristic ofprior art CVT systems utilizing conical contacting faces, is clearlyavoided or reduced to a high degree in the CVT constructed according tothe present invention.

[0116] An additional advantage in the preferred embodiments of theinvention described below is that the force required to radiallydisplace the contact elements is relatively small. Thus the contactplates move perpendicularly to the axis of rotation exactly as the teethof ordinary meshing gears. Such an arrangement effects a more efficienttorque transfer, reduces friction, wear, and the possibility ofbreakage, and also permits transmission changes by the application ofrelatively small forces.

[0117] The foregoing mechanism of action and advantages, as well asadditional advantages, attainable thereby will be more readily apparentfrom the description below of a number of preferred embodiments of theinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0118]FIGS. 1-4 illustrate a continuously-variable transmission CVTconstructed in accordance with the invention and including two rotarymembers, namely a variable-diameter toothed wheel 10 rotatable aboutrotary axis RA, and a fixed-diameter toothed wheel 20 rotatable aboutits rotary axis 25, parallel to rotary axis RA.

[0119] The variable-diameter toothed wheel 10 includes a pair ofaxially-spaced discs 11, 11, formed with a plurality ofradially-extending slots 12, 12, receiving the opposite ends of anannular array of coupling elements 13.

[0120] The construction of each of the coupling elements 13 is moreparticularly illustrated in FIG. 3. It includes a mounting plate 14having its opposite ends slidably received within slots 12, 12 of thewheel discs 11, 11. It also includes a contact plate 15 pivotallymounted at 16 to the mounting plate. The opposite ends of the mountingplate 14 are thickened, as shown at 17, to define tracks 18 to beslidably received within the slots 12, 12 of the wheel discs 11, 11. Oneend of each slot 12, 12 may be widened (not shown) to facilitate theapplication and removal of the mounting plates 14 from the slots 12 ofthe discs 11.

[0121] It will be seen that mounting plates 14, being slidably receivedwithin the slots 12, 12, permit the coupling elements 13 to be displacedradially with respect to the toothed wheel 10 to change the effectivediameter of the toothed wheel. It will also be seen that the pivotalmountings 16 of the contact plates 15 permit one end (e.g., 15′) of eachcontact plate to be moved upwardly to define a projection to engage adepression in wheel 20, and causes the opposite end (e.g., 15″) to bepressed downwardly to define a depression to be engaged by a projectionin wheel 20. Coupling elements 13 are thus of a self-adaptiveconfiguration enabling them to adapt themselves to the configuration ofthe projections and depressions in the fixed-diameter toothed wheel 20in all effective diameters of the variable-diameter toothed wheel 10.

[0122] The construction of the fixed diameter toothed wheel 20 is moreparticularly illustrated in FIG. 4. It is formed on its outercircumference with a first series of projections and depressions 21, 22on one side, and a second series of projections and depressions 23, 24on the opposite side, in staggered relationship to the first series;that is, a projection, (e.g., 21) formed on one face is axially alignedwith a depression (e.g., 24) formed on the opposite face along a lineparallel to the rotary axis RA of wheel 10, as well as its own axis 25.It will also be seen that, since toothed wheel 20 of a cylindricalconstruction (rather than of a conical construction), the pitch of theprojections 21, 22 on one side face of the wheel is exactly the same asthe pitch of projections 23 and depressions 24 on the opposite side,even though the two series of projections and depressions are in theabove-described staggered relationship.

[0123] In the construction of the toothed wheel 20 illustrated in FIGS.1 and 4, this staggered relationship between the two series ofprojections and depressions 21-24 is produced by forming the projectionsand depressions obliquely to the rotary axis 25 of the toothed wheel 20.Such an arrangement thus produces a gradual transition between theseries of projections and depressions 21, 22 on one side, and the seriesof projections and depressions 23, 24 on the opposite side.

[0124] It will thus be seen that the transmission illustrated in FIGS.1-4 is continuously-variable by moving the two discs 11, 11 of thevariable-diameter toothed wheel 10 towards or away from each other.Moving the discs towards each other forces the coupling elements 13 ofthe toothed wheel 10 radially outwardly, to thereby effectively increasethe diameter of the toothed wheel; whereas moving the discs away fromeach other causes the coupling elements 13 to move inwardly, therebydecreasing the effective diameter of the toothed wheel.

[0125] It will also be seen that, irrespective of the effective diameterof the toothed wheel 10, its contact plates 15 of the coupling elements13, when engaged by the projections and depressions 21-24 of thefixed-diameter toothed wheel 20, will automatically pivot on the pivot16 to engage, at the opposite ends of the contact plates 15, oppositelysloped surfaces of the projections and depressions 21-24, and thusself-adapt themselves to the configuration of those projections anddepressions. The opposite ends of each contact plate 15 move the samedistance, but in opposite directions, such that the mean distancebetween the two ends should be the same for each pivotal position of thecontact plate.

[0126] It will further be seen that the engagement of the contact plates15 with the projections and depressions 21-24 of the toothed wheel 20will be along single line contacts; and further, that the pitch of theprojections and depressions 21-24 is the same at both side faces ofwheel 20, the pitch of the projections and depressions along each lineof contact will be the same for all points on the respective line ofcontact. Accordingly, the problem of creating undue differentialstresses in the coupling elements along the lines of contact,characteristic of CVTs having projections and depressions on conicalsurfaces, is avoided or greatly reduced.

[0127] Several ways of moving the two discs 11, 11 towards or away fromeach other in order to change the effective diameter of the toothedwheel are described below particularly with respect to FIGS. 29-37.

[0128] While in FIGS. 1-4, the coupling between the variable diametertoothed wheel 10 with the fixed diameter toothed wheel 20 is effected onthe outer periphery of the coupling elements 13, it will be appreciatedthat the coupling can also be effected on the inner periphery of thecoupling elements, whereupon the fixed diameter toothed wheel 20 will belocated within the variable diameter toothed wheel 10. Similarly, thefixed diameter toothed wheel 20 could be in the form of a ring in whichthe projections and depressions are on the inner periphery of the ringand are coupled to the outer periphery of the variable diameter toothedwheel located within the ring.

[0129] It will also be seen that the CVT illustrated in FIGS. 1-4transmits mechanical motion in a predetermined direction between the tworotary members (10, 12), namely about their rotary axes; that one member(wheel 10), includes a coupling element (13), and the other member(wheel 20) has an engagement surface formed with a topography ofprojections and depressions 21-24 in a periodic pattern of the samepitch in every cross-section parallel to the direction of motion; thatthe coupling element 13 of wheel 10 is placeable on the engagementsurface of wheel 20 at any point along the direction of motion and reston that surface along at least one line of contact; that couplingelement 13 has at least one point, namely the median point in allinclined positions of contact plate 15, that does not change itselevation above wheel 20 for any of the points of rest of couplingelement 13 and that the line of contact of contact plate 15 of couplingelement 13 rests at least partially on a positive slope and partially ona negative slope of the surface formed with the projections anddepressions 21-24.

[0130] It is to be noted in FIG. 3 that pivot axis 16 of the contactplate 15, carried by each of the coupling elements 13, lies under thecontact surface of the contact plate. A situation is therefore createdin which the mean height of the two points of contact is lower when theplate is level than when the plate is inclined. This may be suitablycompensated for by appropriately configuring the projections anddepressions 21-24 in the fixed-diameter toothed wheel 20.

[0131]FIG. 5 illustrates another construction of coupling element,therein designated 13 a, to define the self-adaptable projections anddepressions in the variable-diameter toothed wheel 10 for use with thetoothed wheel 20 of FIGS. 1 and 4. In the construction illustrated inFIG. 5, the coupling element 13 a includes a mounting plate or holder 14a rotatably mounting a contact plate 15 a in the form a disc having aflat contact edge 16 a and a semi-circular lower edge 17 a rotatablewithin a semi-circular groove 18 a formed in the mounting plate 14 a.Thus, when disc 15 a is rotated in one direction, one end 16 a″ of itscontact edge 16 a is moved in one direction to define a projectionengageable with a depression on wheel 20, and the opposite end 16 a″ ofits contact edge is moved in the opposite direction the same amount todefine a depression to be engaged by a projection on wheel 20.

[0132] An advantage in the rotatable disc configuration of FIG. 5 isthat the center of rotation of the disc 15 a can be located centrally ofthe top edge 16 a of the disc, such that the mean height of the pointsof contact will remain the same in all rotational positions of the disc.Additional accessories may be added, such as ball bearings, in order toreduce friction during the rotation of the contact disc 15 a.

[0133]FIGS. 6 and 7 illustrate a variation in the construction of thefixed-diameter toothed wheel 20, therein designated 20 a. Thus, as shownin FIGS. 6 and 7, toothed wheel 20 a also includes a first series ofprojections and depressions, 21 a, 22 a on one side, and a second seriesof projections and depressions 23 a, 24 a on the opposite side, instaggered relationship to the first series, such that a projection inone series is axially aligned with a depression in the other series. Inthis case, however, instead of having a gradual transition between thetwo series of projections as in FIGS. 1 and 4, two discs, each formedwith one series of projections and depressions, may be fixed on acentral ring 25, so that the transition between the two series isstepped, rather than gradual. However, the operation is basically thesame as described above with respect to toothed wheel 20 illustrated inFIGS. 1 and 4, in that the fixed projections and depressions 21 a-24 aon the toothed wheel 20 a are of the same pitch from one side face tothe opposite side face, and cause the self adaptable coupling elements13 in the variable-diameter toothed wheel 10 to automatically adaptthemselves to the configuration of the projections and depressions onthe toothed wheel 20 a. They thus provide line contacts with theprojections 21 a-24 a of the toothed wheel 20 a in all effectivediameters of the wheel 10. The construction of FIGS. 10 and 11 thus alsoeffects a non-slip coupling, without producing excessive differentialstresses along the contacted surfaces, in all conversion ratios of thetransmission in the same manner as described above with respect to FIGS.1-4.

[0134]FIG. 8 illustrates a self-adaptive coupling element 13 b which maybe used in the variable-diameter toothed wheel 10 shown in FIGS. 8 and9. Such a coupling element also includes a mounting plate 14 b formounting the coupling element 13 b in a radially-displaceable mannerwithin the radial slots 12, 12 in the two discs 11, 11 of thevariable-diameter toothed wheel 10 (FIGS. 1, 3). In this case, however,instead of including a pivotal contact plate (corresponding to contactplate 15 in FIG. 3), the coupling element 13 b illustrated in FIG. 8includes a pair of contact elements in the form of teeth 15 b ₁, 15 b ₂,on the opposite sides of the mounting plate 14 b and actuated togetherby a pivotal rocking bar 16 b. The arrangement is such that when thetooth 15 b at one end is moved in one direction to define a projection,the tooth 15 b at the opposite end is moved in the opposite direction todefine a depression.

[0135] It will thus be seen that the self-adaptive coupling elements 13b (FIG. 8) cooperate with the toothed wheel 20 a of FIGS. 6 and 7 insubstantially the same manner as described above with respect tocoupling elements 13 and toothed wheel 20 of FIGS. 1-5. Thus, thecoupling elements 13 d (FIG. 8), when engaged by the double toothedwheel 20 a of FIGS. 6 and 7, are also individually displaced to engage,at their opposite ends 15 b ₁, 15 b ₂, oppositely sloped surfaces of theprojections and depressions 21 a-24 a, thereby adapting themselves tothe configuration of the latter projections and depressions to effect acoupling therewith along lines of contact, in this case two lines ofcontact, in all the radial displacement positions of the contactelements 13 b, except in this case, each contact element produces twolines of contact, by teeth 15 b ₁ and 15 b ₂, respectively interruptedby the space between the two sections of the toothed wheel 20 a.

[0136]FIG. 9 illustrates a manner of compensating for the difference inthe mean height of contact plate 15 in its level and inclined positionswhen using the fixed-diameter toothed wheel 20 a of FIGS. 6 and 7. Thus,as shown in FIG. 9, the contact plate, therein designated 15 c, isslightly curved and is formed with a central recess 15 c′ in alignmentwith the pivotal axis 16 c, such as to assure that for any two points ofcontact, and for any given inclination of the contact plate, the meanheight will be the same.

[0137]FIG. 10 illustrates contact plate 15 d, corresponding to contactplate 15 in FIG. 3, but of a cross-section which is the same as thecross-section of a tooth in a standard gear wheel. Contact plate 15 dshown in FIG. 10 is also pivotal on a pivotal mounting, shown at 16 d,to enable the contact plate to self-adapt itself to the configuration ofthe fixed projections and depressions, in the same manner as describedabove with respect to FIG. 3. Among the variety of possibilities fordesigning the curves of the projections and depressions, it is possibleto choose a shape, such as the involute curve common in standard gearwheels. Such a curved shape increases the range of contact between thefixed projections and the self-adapting projections beyond the topmostengagement points.

[0138]FIG. 11 illustrates such a construction wherein a projection shownat 15 e has one side 15 e′ shaped in the form of an involute curve, andthe other side 15 e″ shaped as its inversion, so that the mean height ofthe contact plate 15 c will remain the same.

[0139] While the technique illustrated in FIG. 11 produces a tooth formwhich is asymmetric, this does not significantly affect the operationsince the pressure is always exerted in the direction of rotation. Thismeans that, for the most part, one side only of the contact plate isengaged. In this case, the transmission can be designed so that thepressure will be exerted on the side which is of the involute shape. Thecurved sides are to be such that the projection carries out the task ofpushing the contact plate 15 e towards the opposing depression whentaking into consideration the thickness of the contact plate.

[0140] Other possible constructions may be used for the self-adaptivecoupling elements 13 in the toothed wheel of FIGS. 6 and 7. For example,the teeth pair arrangement illustrated in FIG. 8 could be used, butwherein the two teeth are actuated by fluid pressure rather than by arocking bar 16 b, such that when one tooth is moved downwardly to definea depression, the other tooth is moved upwardly to define a projection.

[0141]FIG. 12 illustrates a continuously-variable transmission similarto that described above with respect to FIGS. 1-4, except that thetransmission member meshing with the variable-diameter, rotary wheel 10is not a rotary member (e.g., 20, FIG. 1), but rather is a toothed rack20 b mounted for linear movement rather than for rotary movement. In allother respects, rack 20 b may be the same as toothed wheel 20 in FIGS.1-4, or toothed wheel 20 a in FIGS. 6 and 7.

[0142] Thus, rack 20 b also includes two series of fixed projections anddepressions on its opposite side faces, shown at 21 b-24 b, both of thesame pitch and engageable with the projections and depressions definedby the coupling elements 13 of the variable-diameter toothed wheel 10.Coupling elements 13 thus also automatically also adapt themselves to becomplimentary to the configuration of the projections and depressions inthe rack 20 b in all effective diameters of the variable-diameter rotarywheel 10 such that the opposite ends of the contact plate (15) of eachcoupling element (13) along contact lines with the oppositely-slopedsurfaces of the projections and depressions of the rack in alldisplacements positions of the coupling elements thereby effecting anon-slip coupling between the toothed wheel and the rack in alltransmission ratios. In addition, since the pitch of the projections anddepressions in the rack 13 the same at both side faces of the rack, thisarrangement also avoids the creation of undue differential stresses inthe coupling elements along the lines of contact at each effectivediameter of wheel 10.

[0143] While FIG. 12 illustrates a rotary member of a particularconstruction coupled to a rack of a particular construction, it will beappreciated that the transmission could include various constructions ofrotary members and/or racks, as described herein, for example.

[0144]FIG. 13 illustrates a continuously-variable transmission alsoincluding a variable-diameter toothed wheel 10 as in FIG. 1, but with aclosed-loop chain 30 as the other transmission member, instead of atoothed wheel (20, FIG. 1). In the transmission illustrated in FIG. 12,an end of the closed-loop chain 30 is applied around the couplingelements 13 of the variable-diameter toothed wheel 10 rotatable aboutrotary axis 10′, and the opposite end of the chain is applied around asprocket wheel 35 rotatable about rotary axis 35′.

[0145] A chain tautening pinion 36 mounted at one end of a pivotal arm37 maintains chain 30 taut under all effective diameters of the toothedwheel 10.

[0146]FIG. 14 illustrates a similar arrangement except, instead ofapplying the end of the chain 30 around a sprocket wheel (35, FIG. 13)it is wrapped around another variable-diameter toothed wheel 10 of likeconstruction as toothed wheel 10, such that when the effective diameterof one toothed wheel decreases, that of the other increases acorresponding amount, thereby maintaining the chain 30 taut under alltransmission ratios.

[0147] Chain 30, in both FIG. 13 and FIG. 14, is similarly constructedas toothed wheel 20 (FIG. 1), or toothed wheel 20 a (FIG. 10), toinclude the projections and depressions of fixed configuration. Theprojections and depressions on the chain are also of the same structureon the opposite side faces of the chain, and are also cooperable withthe projections and depressions of self-adaptive configuration definedby the coupling elements 13 in the variable-diameter toothed wheel 10 toproduce the same type of non-slip line contacts between the couplingelements, during all effective diameters of wheel 10, as described abovewith respect to FIGS. 1-12.

[0148]FIGS. 15-19 illustrate various constructions of chains that may beused for this purpose.

[0149] Thus, as shown in FIG. 15 (and also in FIG. 13), the chain 30 hastwo series of projections and depressions on its opposite sides both ofthe same pitch. One series includes projections 31 and depressions 32;and the other series includes projections 33 and depressions 34 in astaggered relation thereto, such that each projection (e.g., 31) in oneseries is axially aligned with a depression (e.g., 34) in the otherseries along the rotary axis 10′. This may be done, as shown in FIG. 15,by using links of the same configuration but inverting themalternatively in each series.

[0150] As shown in FIG. 16, the mean distance between eachaxially-aligned projection 31 and depression 34, and eachaxially-aligned projection 32 and depression 33, is at a common medialpivot line MPL which passes through the pivot axis PA, PB of the chainlinks.

[0151]FIG. 17 schematically illustrates the points of contact of thechain links with the contact plates of the coupling elements (e.g.,contact teeth 15 b ₁, 15 b ₂ of coupling element 13 b, FIG. 8). In FIG.17, the contact of the contact plate with a projection is shown by curva“a”, and with a depression is shown by curve “b”. It will be seen thatthe mean distance between the two curves is the median contact line MCL;i.e., the median distance between any two points along curves “a” and“b” always falls on line MCL. Thus line MCL, which is the effectivediameter of the rotary member, remains the same for all contact pointsbetween the contact plates and the chain links, and is a constantdistance below the median pivotal line MPL.

[0152] It will therefore be seen that the contact plates will adjustthemselves automatically to the configuration of the chain. Thus theyalso provide full contact, along the two colinear contact lines ofengagement of teeth 15 b ₁, 15 b ₂ (FIG. 8), with oppositely slopedsurfaces of the projections and depressions 31-34 in the chain 30, whichdoes not allow any slippage, in all radial positions of the contactelements 13, that is, in all effective diameters of the toothed wheel10. In addition, since the pitch of the projections and depressions31-34 in the chain 30 are of the same width, all the points on each lineof contact with the projections and depressions are of the same pitch,thereby also avoiding the creation of stresses in the coupling elementsalong the lines of contact.

[0153] The two series of projections and depressions 31, 32 and 33, 34,respectively, in the chain 30 illustrated in FIG. 15 includetwo-elements links L₁, L₂, both defining a projection (e.g., 31, 33) anda depression (e.g., 32, 34), but alternatingly reversed in the chain.The transitions between succeeding projections and depressions arestepped transitions, analogous to the stepped transitions in the toothedwheel 20 a of FIG. 10.

[0154]FIG. 18 illustrates another chain construction includingsingle-element links which may also be alternatingly reversed. Thus, asshown in FIG. 18, the links L₃, L₄ are assembled in an alternatinglyreversed manner such that two series of projections and depressions 31′,32′ and 33′, 34′, respectively, would be defined on each side of thechain, as described above with respect to FIG. 15.

[0155]FIG. 19 illustrates a single-element chain link alternatinglyreversed, as shown by links L₅, L₆, wherein the transitions between thetwo series of projections and depressions, therein designated 31 a, 32 aand 33 a, 34 a, respectively, include gradual transitions, analogous tothe structure of the toothed wheel 20 shown in FIGS. 1 and 4. In eachsingle element links L₅, L₆, shown in FIG. 19, one end of the link isprovided with a male connector MC, and the opposite end is provided witha female connector FC, for assembling a chain of such links.

[0156] As described above with respect to the chain construction of FIG.15-17, the projections and depressions in the chain constructions ofFIGS. 18 and 19 will also cause the radially-displaceable couplingelements 13 in the variable-diameter toothed wheel 10 to automaticallyadjust themselves to the projections and depressions in the chain in allradial positions of the coupling elements 30 to produce line contactswith the chain which do not slip and which do not create stresses alongthe contact lines

[0157]FIG. 20 illustrates a belt, therein generally designated 30 b,which may be used in the continuously-variable transmission of FIGS. 13or 14 in lieu of the chain 30 or 30 a. Thus, belt 30 b is alsoconstructed of two series of projections and depressions 31 b, 32 b, and33 b, 34 b, respectively, having the same pitch between the oppositesides of the belt, and cooperable with the coupling elements 13 in thevariable-diameter toothed wheel 10 of FIG. 1 to cause the lattercoupling elements automatically to adapt themselves to the configurationof the projections and depressions 31 b-34 b in all radial positions ofthe coupling elements 13, in the same manner, and to produce the sameresults, as described above. Belt 30 b illustrated in FIG. 20 includesgradual transitions between the two series of projections 31 b, 32 b and33 b, 34 b, respectively, analogous to the projections and depressionsin the chain links of FIG. 19, and in the toothed wheel 20 of FIGS. 1and 3.

[0158]FIG. 21 illustrates a variation in the belt, therein designated 30c, in which the transitions between the two series of projections anddepressions 31 c, 32 c and 33 c, 34 c, respectively, are steppedtransitions, analogous to the chain links of FIGS. 15-18, and the doubletoothed wheel 20 a of FIGS. 6 and 7.

[0159]FIG. 22 illustrates another arrangement that may be used,including a closed loop chain 30 f cooperable with self-adaptivecoupling elements 13 f carried by the variable-diameter toothed wheel(e.g. 10, FIG. 1). In this case, the chain 30 f also includes a seriesof projections and depressions 31 f, 32 f on one side, and anotherseries of projections and depressions 33 f, 34 f on the opposite side instaggered relationship with, and of the same pitch as, the first seriesof projections. Each of the coupling elements 13 f carried by thevariable-diameter toothed wheel (e.g., 10, FIG. 1) includes a holder 14f carrying a shifting plate 15 f formed with a pair of teeth 16 f, 17 f,at its opposite ends, separated by a recess 18 f. Plate 15 f is shiftedon rollers 19 f. The recess 18 f is formed with sloping walls definingthe teeth 16 f, 17 f at its opposite ends, and is dimensioned accordingto the width of the chain 30 f. Thus, the chain may slide into therecess 18 f, causing the plate 15 f to shift appropriately in order toreceive the chain.

[0160] It will thus be seen that in the FIG. 22 construction, as in thepreviously-described constructions, the projections and depressions 31f-34 f of the chain 30 f cause the coupling elements 13 f in the toothedwheel 10 to self-adapt themselves to the configuration of theprojections and depressions 31 f-34 f in all radial positions of thecoupling elements 13 e. It will also be seen that in each of the twocolinear lines of contact (by teeth 16 f, 17 f, respectively) the twoteeth at the opposite ends of the contact plate (15 f) will engageoppositely-sloped surfaces of the projections and depressions in thechain 30 f, to thereby effect a non-slip coupling therewith, and thepitch of the projections and depressions will be the same along allpoints on each contact line, thereby avoiding the creation of stressesalong the contact lines.

[0161]FIG. 23 illustrates a further construction of chain link, thereindesignated 30 g, which may be used with a particular construction ofcoupling element shown in FIG. 24, therein designated 13 g, in thetoothed wheel (10, 10 a) which will produce the same basic operation asdescribed above. Chain 30 g illustrated in FIG. 23 also includes twoseries of projections and depressions, namely one series consisting ofprojections and depressions 31 g, 32 g along one side of the chain, anda second series of projections and depressions 33 g, 34 g, on theopposite side, and of the same itch as the one series.

[0162] As distinguished from the previous constructions, however, thetwo series of projections and depressions are in axial alignment witheach other, and are not in a staggered relationship as in the previouslydescribed embodiments. In this case, the respective coupling element 13g on the variable-diameter toothed wheel (e.g., 10, FIG. 1) is modifiedto enable it to self-adapt to the configuration of the chain 30 g havingthe two series of projections and depressions in an aligned, rather thanstaggered, arrangement. This is done as follows:

[0163] In FIG. 23, the pitch of the series of projections anddepressions 31 g, 32 g and 33 g, 34 g, respectively, is shown as “P”;thus the distance between corresponding points of a projection and of adepression is one-half the pitch, or P/2.

[0164] In order to have the coupling elements on the toothed wheelproduce the above-described self-adapting function with the chain 30 gillustrated in FIG. 23, each coupling element 13 g is of theconstruction shown in FIG. 24. In such a construction, the couplingelement 13 g includes a mounting plate 14 g which is slideable withinthe radial slots of the toothed wheel as described above, and a contactplate pivotally mounted to the mounting plate, analogous to contactplate 15 in FIG. 3. However, in this case the contact plate, generallydesignated 15 g in FIG. 24, is not constituted of a single section as inFIG. 3, but rather is constituted of two sections 15 g ₁, 15 g ₂,interconnected by a juncture section 15 g ₃, which is pivotally mountedat 16 g to the mounting plate 14 g.

[0165] The two sections 15 g ₁ and 15 g ₂ are parallel to each other butare offset a distance exactly equal to one-half the pitch (P/2) betweenthe projections and depressions in the chain 30 g. Thus, when thecoupling element 13 g illustrated in FIG. 24 is used with the chainillustrated in FIG. 23, one section 15 g ₁ of the contact element willbe aligned with a projection in the chain, whereas the other section 15g ₂ will be aligned with a depression in the chain. Accordingly, thecontact elements 13 g also self-adapt their configurations to theconfigurations of the projections and depressions 31 g-34 g in the chain30 g in the same manner as described above, to produce non-slip,unstressed contact lines for all radial positions of the contactelements 13 g in the toothed wheel.

[0166] The arrangement illustrated in FIGS. 23 and 24 thus enables thenovel transmission to be used with almost any conventional chainstructure. It will be appreciated that the same technique described withrespect to FIGS. 23 and 24 for chains could also be applied for belts,as described with respect to FIGS. 20 and 21, and for toothed wheels, asdescribed with respect to FIGS. 1 and 6.

[0167]FIGS. 25 and 26 schematically illustrate other manners ofproviding coupling elements on one transmission member (e.g., couplingelements 13 on the variable-diameter toothed wheel 10, FIG. 1) of aself-adaptive configuration which enables adapting themselves to thefixed-configuration projections and depressions on the othertransmission member, (e.g., toothed wheel 20, but using a single seriesof projections and depressions) in all radial positions of the onetransmission member.

[0168] In FIG. 25, the transmission member having thefixed-configuration projections and depressions is schematically shownat 40, and the projections and depressions are indicated at 41 and 42,respectively; whereas, each of the coupling elements of self-adaptiveconfiguration is schematically shown at 43. As seen in FIG. 25, each ofthe self-adaptive configuration coupling elements is in the form of anassembly pivotal on an axis 44 perpendicular to the direction ofmovement of transmission member 40 and having a pair of arms 45, 46parallel to the pivotal axis 44 of pivotal assembly 43 and engagingspaced points on the projections and depressions of member 40 in allpivotal positions of the pivotal assembly.

[0169]FIG. 25 schematically shows four positions of a pivotal assembly43. In all such positions, both of the arms 45, 46 of each pivotalassembly engage two spaced points on the opposite sides of a projectionor of adjacent projections, in the transmission member 40, and therebyeffect a non-slip coupling therewith in all effective diameters of thevariable-diameter toothed wheel.

[0170]FIG. 26 schematically illustrates a similar arrangement, whereinone transmission member 40 a is provided with the fixed projections anddepressions 41 a, 42 a; and the other transmission member is providedwith the self-adaptive coupling elements shown as pivotal assemblies 43a pivotal about an axis 44 a perpendicular to the direction of movementof transmission member 40 a. In the arrangement illustrated in FIG. 26,however, the pivotal assembly 43 a includes a pair of spaced teeth 45 a,46 a, which are adapted to engage spaced points on the projections anddepressions 41 a, 42 a of transmission member 40 a such as to effect thenon-slip coupling therewith in all effective diameters of the rotarymember carrying the coupling elements 43 a.

[0171]FIGS. 25 and 26 also clearly show how each of the self-adaptivecoupling elements engage, at its opposite ends, oppositely slopedsurfaces of the projections and depressions in the other transmissionmember (40, 40 a, e.g., a toothed wheel, a chain, a belt, or a toothedrack as described above) to effect a non-slip coupling with theprojections and depressions along lines of contact therewith.

[0172] Since, in these embodiments, the other transmission member (40,40 a) is of uniform thickness, the pitch of their projections anddepressions would be the same at all the points on each line of contact,thereby avoiding the creation of undue differential stresses in thecoupling elements along the lines of contact in the same manner asdescribed above.

[0173] Various techniques may be used to reduce noise and vibrationswhich may arise as a result of the movements of the self-adaptingcoupling elements and their high speed engagement of thefixed-configuration projections and depressions of the other couplingelements. FIGS. 27 and 28 illustrate two possible solutions to the noiseand vibration problem.

[0174]FIG. 27 illustrates the toothed wheel 50 with one series ofprojections and depressions 51, 52 along one side, and a second seriesof projections and depressions 53, 54 along the opposite side. In orderto reduce noise and vibration, the outer edges of the two series ofprojections and depressions are covered by, or defined by, rings 55, 56,respectively, of rubber or other cushioning material fixed in place bypins 57.

[0175] The coupling elements on the other transmission member, which areof a self-adaptive configuration, could similarly be provided with arubber or other cushioning material, as shown in FIG. 28. The couplingelements shown in FIG. 28, and therein designated 60, are of the pivotaltype, as for example in FIG. 3. Each coupling element includes a contactplate 61 pivotally mounted at its center 62 such that when one end ismoved upwardly, the opposite end is moved downwardly. In this case, theopposite ends of the contact plate 61 are provided with pads of rubberor other cushioning material, as shown at 63 and 64, to reduce noiseand/or vibration.

[0176] Another possible technique is to replace the rubber pads withspring elements, such as elastic steel tabs, which would be struck bythe pivotal contact plates before contact with the toothed wheel (e.g.,of metal), and thus cushion the strikes. A still further possibilitywould be to install oil channels on the toothed wheel, so that the oilis pumped under pressure from the direction of the wheel ofcomplimentary symmetry in the direction opposite to the motion of thepivotal contact plates, and thus cushion their strikes.

[0177] Many other constructions of variable-diameter toothed wheelscould be used, other than the one illustrated in FIGS. 1 and 2 includingtwo conical discs each formed with an annular array of radial slots forreceiving the radially-displaceable coupling elements (13).

[0178]FIG. 29 illustrates one such construction toothed-wheel (withoutthe coupling elements), and FIG. 30 illustrates a coupling element foruse with the toothed wheel of FIG. 29.

[0179] The toothed-wheel illustrated in FIG. 29, and therein designated70, includes two discs 71, 72. Disc 71 is preferably conical and isformed with an annular array of radially-extending slots 73, whereasdisc 72 carries an annular array of radially-extending triangular-shapedribs 74 receivable within slots 73.

[0180] Each of the coupling elements 75 illustrated in FIG. 30 is of therotary disc construction shown in FIG. 5, but adapted for use with thetoothed-wheel 70 of FIG. 29. Thus, each coupling element 75 includes amounting plate 76 rotatably mounting a disc 77 having an upper flat edge77′ which serves as the contact surface for the coupling elements of theother transmission member, (e.g., wheel 20, FIG. 1). Mounting plate 76is formed along one edge with a slot 76 a slideably receiving thediagonal edge of a triangular rib 74 on disc 72; and the opposite end ofmounting plate 76 is formed with a rib 76 b to be slideably receivedwithin a slot 73 of disc 71. A spring 78 may be provided urging mountingplate inwardly of toothed wheel 70, FIG. 29.

[0181] It will thus be seen that moving the two discs 71, 72 away fromeach other will move the coupling elements 75 radially inwardly tothereby decrease the effective diameter of the toothed wheel; whereasmoving the two discs 71, 72 towards each other will move the couplingelements 75 radially outwardly to thereby increase the effectivediameter of the toothed wheel. It will also be seen that contact plate77 will be rotated within the mounting plate 76 in the same manner asdescribed above with respect to FIG. 9 to adapt itself to theconfiguration of an engaged fixed-configuration coupling element: i.e.,when one end of the contact plate is moved upwardly, the opposite end issimultaneously moved downwardly.

[0182] The effective diameter of the toothed wheel 70 illustrated inFIG. 29 can thus be changed by moving the two discs 71, 72 towards oraway from each from other. For each diameter of the toothed wheel,contact plates 77 of the coupling elements 75 will be able to rotatewithin their respective mounting plates 76 to self-adapt theconfiguration of the coupling elements to the fixed-configurationprojections and depressions of the other transmission member (e.g., thefixed-diameter wheel 20, FIG. 1), to thereby effect a non-slip couplingwith that transmission member, in the same manner as described abovewith respect to FIG. 5, for example.

[0183] It will be appreciated that, instead of having a spring bias forthe coupling elements, suitable ribs and grooves could be provided onthe discs and coupling elements for moving tje coupling elementsinwardly as well as outwardly.

[0184]FIG. 31 illustrates another construction of variable-diametertoothed wheel which may be used. The toothed wheel illustrated in FIG.31, therein generally designated 80, also includes a pair of discs 81,82. In this case, however, both discs are flat and are formed with anannular array of radially-extending slots indicated at 81 a, 82 a,respectively.

[0185] The illustrated toothed wheel further includes an annular arrayof triangular plates 83 carried by a common mounting member 84 linearlyand rotatable movable on a central axle 84 a. The triangular plates 83are received within aligned slots 81 a, 82 a of the two discs 81, 82,and all the triangular plates rotate with the discs and are movabletogether by the common mounting member 84 through the slots 81 a, 82 ain the discs.

[0186] The two discs 81, 82 are coupled together by an annular array ofcoupling elements 85. Each of the coupling elements 85 is slidablyreceived at one end within slot 81 a of disc 81, and at its opposite endwithin slot 82 a of disc 82. Each coupling element 85 is furtherprovided with a pivotal contact plate 86, corresponding to contact plate15, FIG. 3, pivotal at 87, such that its opposite ends engageoppositely-sloped surfaces in the projections and depressions in theother transmission member, as described above. The coupling elements maybe spring urged radially inwardly, e.g., as illustrated in FIG. 30, andare radially movable outwardly by the inclined diagonal edges of thetriangular plates 83.

[0187] Mounting member 84 is rotatable about axle 84 a so that all thetriangular plates 83 rotate with the two discs 81, 82, and is axiallymovable with respect to axle 84 a to move the coupling elements radiallyinwardly or outwardly in their respective slots, and thereby to vary theeffective diameter defined by the coupling elements 85 between the twodiscs 81, 82.

[0188]FIG. 32 schematically illustrates another variable-diametertoothed wheel, generally designated 90, which includes a conical member91 rotatably mounted at its inner end on a shaft 92, and formed with aplurality of radially-extending slots 93 from its outer large-diameterend to its inner small-diameter end.

[0189] An annular array of coupling elements, each designated 95, areslideably mounted within the slots 93. Each coupling element 95 includesa pivotal contact plate (not shown), similar to contact plate 15illustrated in FIG. 3, for coupling with the other transmission member,such as a toothed wheel, chain or belt as described earlier. A commonactuator member (not shown) moves the coupling elements 95 togetherinwardly or outwardly of their respective slots 92, to thereby changethe effective diameter defined by these coupling elements.

[0190] A toothed wheel construction such as illustrated in FIG. 32 wouldbe particularly useful as the rear gear wheel in a bicycle wherein thecontact plates of the coupling elements 95 are coupled to the sprocketchain of the bicycle, and the common actuator moving the couplingelements 95 is manually controlled or automatically controlled (e.g., bya centrifugal speed sensor), to change the positions of the couplingelements, and thereby the transmission ratio.

[0191]FIG. 33 illustrates another variable-diameter toothed wheel thatmay be used in the continuously-variable transmission, thereindesignated 100. The toothed wheel includes a single disc 101 formed witha plurality of radial slots 102 each receiving one of the couplingelements 103 slidable within the slots 102 in order to change theeffective diameter of the wheel. Coupling elements 103 project throughtheir respective slots 102 on the opposite sides of the disc 101 so asto be engageable with a pair of toothed wheels 104, 105 straddling disc101 and mounted on a common axle 106.

[0192] Each of the coupling elements 102 may be of a self-adaptiveconfiguration according to any of the above-described constructions soas to cause them to engage, at their opposite ends, oppositely-slopedsurfaces of the projections and depressions 106-109 on the outerperiphery of the two stepped wheels 104, 105 when engaged by thosewheels in the manner described above, and thereby to effect a non-slipcoupling with the toothed wheels in all radial positions of the couplingelements 103 within the slots 102 of disc 101.

[0193]FIGS. 34-37 illustrate another construction of variable-diametertoothed wheel, therein designated 110. Such a toothed wheel includes twopairs of coaxially-mounted discs, namely an external pair 111, 112, andan internal pair 113, 114. Each of the external pairs 111, 112 includesan annular array of radially-extending slots of a curved configuration111 a, 112 a; whereas each of the internal discs 113, 114 includes anannular array of radially-extending slots 113 a, 114 a, of a straightconfiguration. The two external discs 111, 112, are mounted for rotationtogether by an inner ring 115 a, and the two inner discs 113, 114 aremounted for rotation together by another ring 115 b enclosing the innerring 115 a.

[0194] The toothed wheel 110 illustrated in FIG. 34 further includes anannular array of coupling elements 116. As more particularly illustratedin FIG. 37, each of the coupling elements 116 includes a U-shapedmounting plate 117 fixed to a pin 118 of rectangular cross-sectionhaving cylindrical tips 118 a, 118 b at its opposite ends. Couplingelement 116 further includes a contact element 119 pivotally mounted at119 a to the upper end of the mounting plate 117. Contact element 119 isshown as being of the construction illustrated in FIG. 5 although itwill be appreciated that any other suitable construction could be used.

[0195] Each of the coupling elements 116 is mounted between the twopairs of discs 111, 113 and 114, 112. Thus, at one end of the couplingelement 116, its rectangular pin 118 is received in its respectivestraight slot 113 a in disc 113, and its cylindrical tip 118 a isreceived in the respective curved slot 111 aof the end disc 111.Similarly, at the opposite end of the coupling element 116, itsrectangular-section pin 118 is received within a straight slot 114 a,and its cylindrical tip 118 b is received within the respective curvedslot 112 a. It will be seen that effecting rotation of one pair of discs111, 112 with respect to the other pair of discs 113, 114, will displacethe coupling elements 116 in the radial direction, according to thedirection of rotation.

[0196]FIG. 35 is an end view illustrating the toothed wheel in itsassembled condition; and FIG. 36 illustrates it received within a chain30 for coupling the toothed wheel to another toothed wheel of likeconstruction, such as shown in FIG. 14, or to a sprocket wheel of abicycle, such as shown in FIG. 13.

[0197] In the transmission illustrated in FIG. 36, the toothed wheel 110is driven by the chain 30 to rotate counter-clockwise. The curved slots111 a, 112 a, in the toothed wheel are curved in the opposite directionto the direction of rotation of the wheel. This maintains the chain 30firmly engaged with the coupling elements 116 of the toothed wheel 110and tends to move outwardly in their respective curved slots, therebymaximizing the effective diameter of the toothed wheel. This alsominimizes the effective diameter of the other toothed wheel (not shown)coupled at the opposite end of chain 30. The end result is that thechain 30 is maintained taut and firmly pressed against the couplingelements 116 of the two toothed wheels.

[0198] In addition, an equilibrium of forces is obtained between the twotoothed wheels, both exerting equal and opposite forces on the chain 30,such that a relatively small force is sufficient to change the effectivediameters of the toothed wheels, and thereby to change the transmissionratio defined by them. FIGS. 38 and 39 (as well as FIG. 64 laterdescribed below) illustrate various manners of changing the transmissionratio with such a variable-diameter toothed wheel construction.

[0199] For illustrative purposes, contact 119 in the coupling element116 illustrated in FIG. 37 is of the construction illustrated in FIG. 9,but it will be appreciated that other constructions of contact elementscould be used. In addition, instead of using the contact plate (e.g.,119) for contacting the surface of the projections and depressions to becoupled, the pins (118) projecting from the slot of one of the discscould be used as the coupling element, as in some of the later describedembodiments.

[0200] In FIG. 38, the transmission ratio determined by the effectivediameter of the toothed wheel 110 is controlled by a control lever 120formed with an axial slot 121. The inner end of control lever 120 ispivotally coupled to a pin 122 which is fixed to the two outer discs111, 112, formed with the curved slots 111 a, 112 a. The outer end ofslot 121 in control lever 120 receives another pin 123 fixed to the twoinner discs 113, 114, formed with the straight slots 113 a, 114 a. Theouter end of lever arm 120 carries a weight 124.

[0201] Weight 124 serves as a velocity sensor to automatically changethe transmission ratio in response to velocity. Thus, as the velocityincreases, the weight 124 will move the control lever 120 outwardly bycentrifugal force, to change the effective diameter of the toothed wheelin the direction to make the appropriate change in the transmissionratio between the toothed wheel and the chain, and vice versa. Theso-produced centrifugal force will be amplified by the ratio of theradius of rotation of weight 124 to the radius of rotation of pin 123.

[0202] The transmission system such as illustrated in FIG. 38 isparticularly useful in bicycles.

[0203]FIG. 39 illustrates a CVT system having automatic control usefulin a power-driven vehicle or other power-driven apparatus. Thetransmission system illustrated in FIG. 39, and therein generallydesignated 130, includes two variable-diameter toothed wheels 110 a, 110b, each of the construction described above with respect to FIGS. 34-37,coupled together by a chain 30. For example, shaft 131 of toothed wheel110 a could be the drive shaft, and shaft 132 of toothed wheel 110 bcould be the driven shaft. In the condition illustrated in FIG. 38, thetoothed wheel 110 a has a relatively large effective diameter, and thetoothed wheel 110 b has a correspondingly small effective diameter.

[0204] In FIG. 39, the two drive shafts 131, 132 rotatecounter-clockwise; whereas the curved tracks in the two toothed wheels10 a, 10 b are curved in the opposite direction to the direction ofrotation. As described earlier, such an arrangement maintains the chain30 taut and firmly pressed against the coupling elements in the twotoothed wheels 110 a, 110 b; it also produced an equilibrium of forcesbetween the two toothed wheels such that a relatively small force issufficient to change the effective diameters of the toothed wheels, andthereby to change the transmission ratio defined by them.

[0205]FIG. 39 schematically illustrates a control mechanism for changingthe effective diameters of the two toothed wheels 110 a, 110 b, andthereby the transmission ratio between them. Such a mechanism includes adisc 133 bearing against the end of chain 30 wrapped around toothedwheel 110 b to define the effective inner diameter of that toothedwheel, and thereby, indirectly, also the effective diameter of toothedwheel 110 a. Disc 133 is carried by a piston 134 movable within acylinder 135 by a hydraulic motor 136 controlled by a controller 137.Controller 137 could, in turn, be controlled manually or automatically.It therefore includes a manual control input 138 a to permit manualcontrol, and a velocity sensor input 138 b to permit automatic controlin response to velocity, such as the velocity of vehicle wheels, driveshaft, foot pedals, etc. It further includes a load sensor input 138 cto permit automatic control in response to load, e.g., load on a vehicleengine, on a drill, or the like. Controller 137 includes a further input138 d which enables the user to select the nature of the response to thepreselected condition; for example, in a motorized vehicle, the user mayselect a fast or a slow change in the transmission ratio in response tovelocity.

[0206] Controller 137 could be, or include, a hydraulic pump driven bythe vehicle engine and driving the hydraulic motor 136, such that thehydraulic pump itself serves an engine load sensor for controlling thetransmission in response to engine load.

[0207]FIG. 40 illustrates a transmission system, generally designated140, which is similar to that of FIG. 14, in that it includes a pair ofvariable-diameter toothed wheels 141, 142, coupled together by a chain143, corresponding to toothed wheels 10 and chain 30 in FIG. 14.

[0208] Transmission 140 illustrated in FIG. 40 is controlled by apivotally mounted control bar 144 acting on a control member 145 fortoothed wheel 141, and on another control member 146 for toothed wheel142. The control members 145, 146 may be bearings slidably on the shaftsof their respective toothed wheels 141, 142, and bearing against one ofthe discs in the respective toothed wheel, such that when the controlmember moves the disc inwardly, it increases the effective diameter ofthe toothed wheel, and when it moves the disc outwardly, it decreasesthe effective diameter of the toothed wheel. Any of thepreviously-described arrangements can be used for this purpose, forexample the variable-diameter toothed wheel constructions of FIGS.29-31.

[0209] Control bar 144 is pivotally mounted at its center, with one end144 a coupled to control member 145 for toothed wheel 141, and theopposite end 144 b coupled to control member 146 for toothed wheel 142.It will thus be seen that when control bar 144 is pivoted to movecontrol member 145 outwardly to decrease the effective diameter oftoothed wheel 141, the opposite end will move control member 146inwardly to increase the effective diameter of its toothed wheel 142,and vice versa. Thus, the chain 143 coupling the two toothed wheels 141,142 will always be maintained under constant tension, as described abovewith respect to FIG. 14.

[0210] The pivoting of the bar 144 may be effected manually and/orautomatically in response to a sensed condition. For example, controlbar may be coupled at its pivot point 144 c to a velocity sensor 147,such as a centrifugal device, to automatically change the transmissionratio between the two toothed wheels 141, 142 in response to velocity.Such a transmission is particularly suitable for automotive vehicles,bicycles, and the like.

[0211]FIG. 41 illustrates a transmission control system similar to thatof FIG. 40 but including a different arrangement for maintainingconstant tension in the coupling chain. The control system illustratedin FIG. 41, therein generally designated 150, includes a pair ofvariable-diameter toothed wheels 151, 152, coupled together by a chain153, as illustrated in FIG. 40. Here, however, the control is effectedby a cable 154 which is wrapped around a cylinder 155 for toothed wheel151, and another cylinder 156 for toothed wheel 152. Cylinder 155 iscoupled to a threaded member 157 which in turn, is coupled to one of thediscs in toothed wheel 151, such that when the cylinder is rotated inone direction, the disc of the toothed wheel is moved outwardly todecrease the effective diameter of the toothed wheel, and when thecylinder is rotated in the opposite direction, the disc is movedinwardly to increase the effective diameter of the toothed wheel. Asimilar arrangement is present with respect to cylinder 156 rotated bycable 154 and coupled via threaded member 158 to one of the discs in thevariable-toothed wheel 152 to move the disc outwardly to decrease theeffective diameter of the toothed wheel, or inwardly to increase itseffective diameter.

[0212] Cable 154 may be wound on the two cylinders 155, 156, in oppositedirections, such that pulling the cable in one direction against aspring 159 will cause one toothed wheel to increase its effectivediameter and the other toothed wheel to decrease its effective diameter.The same result may be produced by providing the threaded members 155,156, with threads of opposite directions.

[0213] The arrangement illustrated in FIG. 41 is particularly usefulwhere the variable-diameter toothed wheels 151, 152 are distant from oneanother, such as in a bicycle transmission. One end of cable 154 may befixed to spring 159, and the opposite end may be coupled to a velocitysensor 159 a, such as a centrifugal device, effective to pull the cableharder 154 in one direction in order to automatically adjust thetransmission ratio in response the velocity of the bicycle wheels or ofthe foot pedals.

[0214]FIG. 42 illustrates a CVT system allowing transmission controlwhile the system is rotating. The CVT system illustrated in FIG. 42includes a variable-diameter toothed wheel, generally designated 160, ofthe same construction as described above with respect to FIGS. 34-37,including a pair of outer discs 161, 162 formed with curved slots, and apair of inner discs 163, 164 formed with straight radial slots. Wheel160 rotates on axle 160 a.

[0215] Outer disc 162 formed with the curved slots meshes with a bevelgear 165 rotating on an axle 165 a, which gear rotates a transfer disc166 rotating on axle 160 a. Transfer disc 166 in turn rotates anothergear 167 on axle 167 a, which gear meshes with inner disc 164 forwardwith the straight radial slots of the variable-diameter wheel 160.

[0216] Axle 165 a of gear 165 is fixed in place, whereas axle 167 a ofgear 167 is movable around the central axle 160 a of thevariable-diameter wheel 160. As long as axle 167 a remains in place, theangle between the two wheel discs 162 and 164 will remain constant, andtherefore the effective diameter of wheel 160 will also remain constant.However, as soon as axle 167 a is moved, the angle between the two discs162, 164 changes which thereby moves the coupling pins (116, FIG. 34) inthe radial direction to change the effective diameter of wheel 160 asdescribed above with respect to FIGS. 34-37.

[0217] It will thus be seen that the assembly including gear 165,transfer disc 166, and gear 167, constitutes a differential mechanismwhich permits the CVT system to be controlled while rotating.

[0218] Axle 167 a may be manually controlled and/or automaticallycontrolled in order to change the transmission ratio of the CVT system.For example, any of the automatic controls described above with respectto FIG. 39 can also be used to control the system in FIG. 42.

[0219]FIG. 43 illustrates a CVT system constructed in accordance withthe present invention but including a differential mechanism whichconverts the CVT system to an IVT (infinitely variable transmission)system which enables reaching a transmission ratio down to completestoppage and also reversal, without the need of a clutch. Such a systemis therefore particularly useful for vehicles.

[0220] The system illustrated in FIG. 43, therein generally designated170, includes two variable-diameter toothed wheels 171, 172, each of theconstruction as described above with respect to FIGS. 34-37, and coupledtogether by a chain 173. Axle 172 a of wheel 172 is coupled to a gear174 which gear is in turn coupled to another gear 175, so that gear 175rotates at the same velocity, but in the opposite directions, to axle172 a of wheel 172.

[0221] Gear 175 is coupled to the outer disc 176 of thevariable-diameter wheel 171 via a differential mechanism schematicallyindicated by gears 177, 178 and 179. This differential mechanism remainsstatic without rotation when the transmission ratio is at a point inwhich the speed of gear 175 is identical to the speed of disc 176. Anyvariation in the transmission ratio will cause the central ring gear 179of the differential mechanism to start rotating. In this manner, it ispossible to achieve a transmission capable of converting the enginespeed to any desired output speed, from rest up to the highest speedrequired, without changing the engine speed and without using a clutch.

[0222]FIG. 44 schematically illustrates another transmission system,generally designated 180, which may be used to increase the range oftransmission ratio changes. Such a system may also be used to increasethe load capability of the transmission system, without changing thelocation of the input and output shafts.

[0223] Transmission system 181 includes two (or more) variable-diametertoothed wheels, schematically indicated at 181, 182, fixed together on acommon shaft 183, and two (or more) fixed diameter toothed wheels 184,185, also fixed to rotate together on a common shaft 186. Each of thevariable-diameter toothed wheels 181, 182, and each of thefixed-diameter toothed wheels 184, 185 could be of a construction asdescribed above with respect to FIGS. 1-4. However, a staggeredarrangement is preferably used between toothed wheels 181 and 184 on onehand, and wheels 182 and 185 on the other hand, to increase the range oftransmission ratios permitted by this system without producing undoclearances between the teeth of the toothed wheels 181, 182 which couldresult in slippage. A non-staggered relationship could also be usedwhere it is desired to have the load divided between each pair of wheels181, 184 and 182, 185, thereby increasing the load capability of thetransmission system.

[0224] As further shown in FIG. 44, the two fixed-diameter toothedwheels 184, 185 are mounted on a common shaft 186 which is carried atone end of a pivotal arm 187. The opposite end of pivotal arm 187 ispivoted about axis 188 and rotatably mounts a fixed-diameter toothedwheel 189 meshing with toothed wheel 184.

[0225] It will be seen that the CVT system illustrated in FIG. 44 may beused to increase the transmission-ratio ranges of the system (withoutundue clearances between the teeth which may cause slippage), as well asthe load capability of the system, both without changing the location ofthe input and output shafts (183, 188). It will also be appreciated thatmore than two variable-diameter toothed wheels 181, 182 andfixed-diameter toothed wheels 184, 185 could be used as well as acorresponding number of transfer wheels 189, to further increase therange of transmission ratios and/or the load capability of thetransmission system.

[0226]FIG. 45 is a side view of the CVT system 180 of FIG. 44 moreparticularly illustrating the structure of the variable-diameter toothedwheel 181 (also 182); whereas FIG. 46 is a perspective view moreparticularly illustrating the structure of both variable-diameter wheels181, 182, and the fixed-diameter toothed wheels 184, 185 coupled tothem.

[0227]FIGS. 47-49 illustrate another CVT system, therein generallydesignated 190, including a disc 191 having a central axle 192. Disc 191is formed with an annular array of radial-extending slots 193 eachreceiving a pin 194 slidable within the respective slot towards or awayfrom the central axle 192. The upper end of each slot 193 is enlarged,as shown at 193 a, to facilitate insertion and removal of the pins. Eachpin 194 includes a reduced-diameter section 194 a (FIG. 48) receivedwithin its respective slot 193, a relatively long end section 194 bprojecting outwardly of the disc 191 as shown in FIG. 47, and a shorterend section 194 c at the opposite end of the pin.

[0228] Disc 191, together with the pins 194, thus constitutes avariable-diameter toothed wheel which may or may not rotate about itscentral axis 192.

[0229] The illustrated transmission further includes a gear assembly,generally designated 195, which rotates, with respect to the toothedwheel defined by disc 191 and its annular array of pins 194, around axle192 of the disc. Gear assembly 195 includes a pair of gears 196, 197,mounted on an arm 198, on both sides (or only one side) of disc 191. Asshown particularly in FIG. 49, the two gears 196, 197 have teeth whichare dimensioned so as not to engage each other but to provide aclearance between the teeth which clearance is exactly equal to thediameter of the pins 194 it can be rectangular

[0230] Gear assembly 195 may be moved radially towards or away from thecentral axis 192 of disc 191 and thus change the effective diameter ofthe toothed wheel defined by the pins 194 since the pins will moveradially with the gear assembly 195. Such a movement of the gearassembly thus changes the transmission ratio of the illustratedtransmission. For example, arm 198 of the gear assembly 195 could becoupled to an input shaft, and the central axis 192 of disc 191 could becoupled to an output shaft, so that the transmission ratio between thetwo shafts can be changed by changing the radial position of the gearassembly 195.

[0231] On the other hand disc 191 could be shifted in order to changethe transmission ratio between the two shafts. Such an arrangement wouldprovide the advantage of permitting changes in the transmission ratiowithout moving the input or output shafts.

[0232] Disc 191 thus constitutes one transmission member, and theannular array of pins 194 define the group of projections anddepressions of that member which are radially displaceable towards andaway from axis 192 to change the conversion ratio of the transmission.Gear assembly 195 constitutes a rotary member which is rotatable aboutthe axis 192, and that gears 196, 197 of rotary assembly 195 constitutea series of projections and depressions of fixed configurationengageable with the pins 194 of disc 193 while the gear assembly 195rotates about the central axis 192. Pins 194 within the slots 193 ofdisc 191 are individually displaceable to as to automatically adaptthemselves to the configuration of the teeth on the gears 196, 197 ofgear assembly 195 in all displacement positions of the pins 194 such asto effect a non-slip coupling therewith in all radial positions of thepins.

[0233] It will thus be seen that the CVT system illustrated in FIGS.47-49 transmits mechanical motion between a rotary driving member and arotary driven member having parallel axes of rotation, namely disc 191rotatable about its axis of rotation 192, and gear assembly 190rotatable about its axis of rotation parallel to that of axis 192. Itwill also be seen that the illustrated CVT system includes a pin (194)parallel to the axes of rotation of the driving and driven members; thatone of the rotary members, namely (disc 191) is engageable with each pin194 and allows it a relative -movement only in a direction that isessentially perpendicular to the axes of rotation of gear assembly 195and disc 191, and perpendicular to the pin 194; and that the otherrotary member (gear assembly 195) is engageable with each pin 194 suchthat when gear assembly 195 is rotated, it forces the pin to move inboth the tangential and radial directions, wherein the tangentialmovement is in the direction of the motion, and the radial movement isperiodic around a median radius.

[0234] It will also be seen that the pins 194, constituting theself-adaptive coupling elements, engage oppositely sloped surfaces ofthe gear teeth 196, 197, to thereby effect a non-slip coupling alonglines of contact therewith; and that, since the gears 196, 197, are ofuniform thickness, the pitch of the projections and depressions definedby them is the same along each line of contact with the pins 194,thereby avoiding the creation of undue differential stresses in thecoupling elements along these lines of contact.

[0235]FIG. 50 illustrates another CVT system, therein generallydesignated 200, which includes a variable-diameter toothed wheel of theconstruction illustrated in FIGS. 47-49 acting at one end of the toothedwheel, and another gear assembly acting at the opposite end of thetoothed wheel. To facilitate understanding, those elements in the system200 of FIG. 50 which correspond to the elements described above withrespect to FIGS. 47-49 are identified by corresponding referencenumerals.

[0236] Thus, as shown in FIG. 50, the arm 198 mounting the two gears196, 197 of gear assembly 195 is extended to the opposite side of thetoothed wheel 190 and carries another gear assembly 200 including a pairof gears 201, 202 meshing with the pins 194 at the opposite side of thetoothed wheel disc 191. Arm 197 is provided with an elongated slot 203to accommodate the central axis 191 a of disc 191. The central axis ofthe annular array of pins 194 is shown at 194 a. In the arrangementillustrated in FIG. 50, shaft 204 fixed to gear 201 could serve as theinput shaft to the CVT system, and shaft 205 coupled to gear 196 couldserve as the output shaft, or vice versa.

[0237] The transmission ratio between the input and output shafts canthus be changed, as desired, by suitably shifting disc 191 to shift itscentral axis 191 a with respect to the central axis 194 a of the annulararray of pins 194. Thus, when disc 191 is located such that its axis 191a coincides with the central axis 194 a of the array of pins 194, thetransmission ratio between the input shaft 204 and output 205 will be1:1; and by shifting disc 191, in one or the other direction, thetransmission ratio between the two shafts is accordingly changed.

[0238] It will be appreciated that in the CVT system illustrated in FIG.50, the diameter of the array of pins 194 in the slotted disc 191 is notchanged when changing transmission ratios, but rather the effectiveradius of the respective part of the annular array defined by the pinsis changed. It will also be appreciated that relatively small movementsof the disc 191 are needed to change the transmission ratio since thechanges in the effective radius of the annular array of pins 194 at itsdiametrically-opposite sides are cumulative for changing thetransmission ratio.

[0239]FIG. 51 illustrates a CVT system 210 generally similar to that ofFIG. 50 but including two variable-diameter wheels 190 a, 190 b, each ofthe construction shown at 190 in FIGS. 49 and 50, but with a single gearassembly, generally designated 211, coupled to the radially-displaceablepins 194 of each toothed wheel. Gear assembly 211 includes a mountingmember or arm 212 mounting a gear 213 at one end received within wheel190 a, and another gear 214 at the opposite end received within toothedwheel 190 b. Gear assembly 211 further includes an intermediate gear 215between the two toothed wheels 190 a, 190 b, and cooperable with the twogears 213, 214 coupling them to their respective pins 194 in the twotoothed wheels 190 a, 190 b in the same manner as described above withrespect to FIGS. 47-49.

[0240] For example, the input shaft could be coupled to the center axle192 a of toothed wheel 190 a, and the output shaft could be coupled tothe center axle 192 b of toothed wheel 190 b. When gear assembly 211 islocated precisely at the mid point between the two axles 192 a, 192 b,the effective diameters of the two toothed wheels 190 a, 190 b areequal, and therefore the transmission ratio between the input and outputshafts will be 1:1. Shifting the gear assembly 211 towards the inputshaft 192 a, as illustrated in FIG. 51, will decrease the effectivediameter of toothed wheel 190 a, and increase the effective diameter oftoothed wheel 190 b, or vice versa, thereby changing the transmissionratios between the input and output shafts accordingly. Such anarrangement thus also enables changing the transmission ratios withoutchanging the locations of the input and output shafts.

[0241]FIG. 52-55 illustrate another construction of variable-diametertoothed wheel, generally designated 220, which can be used in the CVTsystem according to the present invention. Here, the toothed wheel isconstructed of two conical discs 221, 222, each formed with a pluralityof radially-extending slots 221 a, 222 a, receiving an annular array ofpin assemblies 223.

[0242] The construction of each pin assembly 223 is more particularlyillustrated in FIG. 53. It includes a pin 224 having aligned oppositeends 224 a, 224 b joined by a circular middle section 224 c. Pinassembly 223 further includes a roller 225 a carried at one side of themiddle circular section 224 c, and a second roller 225 b carried at theopposite side of that section.

[0243] The two conical discs 221, 222 are assembled as shown in FIG. 54,with the two end sections 224 a, 224 b of the annular array of pinassemblies 223 received within their respective slots 221 a, 222 a inthe conical discs 221, 222.

[0244] A pair of gears, one of which is shown at 226 in FIG. 52 carriedwithin toothed wheel 220, engage the inner surfaces of the end section224 a, 224 b of the pin assemblies 223. The two gears 226 are carried atthe inner end of a pair of mounting members 227. The outer ends ofmounting members 227 carry a roller 228 rollable along the outer surfaceof the circular middle sections 224 c of the array of pin assemblies 223within the toothed wheel 220.

[0245] The two conical discs 221, 222 can be moved towards or away fromeach other by any suitable means, e.g. as described above with respectto FIGS. 2, 29, 31 or 32, or as described below with respect to FIG. 64,to change the transmission ratio between the toothed wheel 220 and thegear 226. Thus, when the two discs 221, 222 are moved towards eachother, the pin assemblies 223 are moved outwardly along the conicalsurfaces of the discs, to thereby increase the effective diameter of thetoothed wheel 220, and vice versa.

[0246] As shown in FIG. 55, each slot (e.g., 221 a) in each of the discs(e.g., 221) is recessed along its opposite sides to receive the rollers225 a, 225 b, of each pin assembly 223. The recesses, shown at 221 b,221 c in FIG. 55, are preferably of different depths and are arrangedwith respect to the two discs such that one roller is free to roll inone direction on one disc while cleared from the other disc, and theother roller is free to roll in the opposite direction of the other discwhile cleared from the one disc.

[0247] Roller 228 includes a concave outer surface so as to engage themiddle sections 224 c of the pin assemblies 223 during the rotation ofthe gears 226 with respect to the toothed wheel 220.

[0248] It will be appreciated that the conical surfaces of the two discs221, 222 could be inverted, i.e., such that when the two discs comecloser together, the effective diameter of the wheel increases, ratherthan decreases.

[0249]FIG. 56 illustrates another CVT system, generally designated 230,which includes a variable-diameter toothed wheel 231 and afixed-diameter toothed wheel 232. In this case, the variable-diametertoothed wheel 231 carries the coupling elements defining the projectionsand depressions of fixed configuration, whereas the fixed-diametertoothed wheel 232 carries the coupling elements of the self-adaptiveconfiguration to conform to the configuration of the coupling elementson the variable-diameter toothed wheel 231 in all radial positions ofthe latter elements.

[0250] Thus, as shown in FIG. 56, the variable-diameter toothed wheel231 is formed with a plurality of radial slots 233 each receiving a pin234 carrying an element defining a projection 235, and another elementdefining a depression 236. In one pin 234, the projection 235 anddepression 236 are located at the extreme ends of the pin, whereasin-the adjacent pin, shown at 234′ in FIG. 56, the projection anddepression are located in an intermediate portion of the pin with theprojection 235′ and depression 236′ reversed as compared to pin 234.Such a construction produces a compact arrangement of annular arrays ofprojections and depressions which are radially displaceable within theirrespective slots 233 to vary the effective diameter of the toothed wheel231.

[0251] The fixed-diameter toothed wheel 232 includes an annular array ofindividually pivotal pins 237. Pins 237 are adapted to engage theprojections 235 and depressions 236 in toothed wheel 231 and toself-adapt their configuration to those projections 235 and depressions236 to thereby effect a non-slip coupling with them in all radialpositions of those projections and depressions.

[0252] Preferably, fixed-diameter toothed wheel 232 also includes twotypes of pins, shown at 237 and 237′. Pins 237 are longer than pins 237′and are oriented to engage the projections 235 and depressions 236 ofthe pins 234 carrying them at their opposite ends; whereas pins 237′ areof shorter length and are oriented to engage the projections 235′ anddepressions 236′ of the pins 234′ located in the intermediate portionsof pins 234′. Such an arrangement provides a compact disposition of thepins 237 and 237′, and of the projections 235, 235′ and depressions 236,236′, with assurance that no excessive clearances will be produced whenthe effective diameter of toothed wheel 231 is increased.

[0253]FIG. 57 illustrates a CVT system similar to that of FIG. 6, butincluding two variable-diameter toothed wheels, each of the sameconstruction as one-half of the toothed wheel 231 in FIG. 56 (andtherefore also identified by the same reference numeral 231) coupledtogether by a chain 239. It will be appreciated that the two toothedwheels 231 in FIG. 57 include the pins 234 carrying the projections 235and depressions 236 as in FIG. 56, whereas the chain 239 carries thepivotal pins 237 which are self-adaptive to the configurations of theprojections and depressions, as described with respect to FIG. 56. Itwill also be appreciated that the chain 239 is always maintained tautsince a reduction in the effective diameter of one wheel 231 isaccompanied by an increase in the effective diameter of the other wheel231, as described above with respect to FIG. 14.

[0254]FIG. 58 illustrates a CVT system 240 also including two toothedwheels 241, 242, but in this case the coupling elements of both wheelsare displaceable radially to thereby change the effective diameter ofthe respective wheel. In addition, the two toothed wheels 241, 242 areof like construction, but differently oriented with respect to eachother. This enables a CVT system to be constructed with two (or more)toothed wheels of like construction, thereby substantially reducinginitial tooling, maintenance, and inventory costs.

[0255] As shown in FIG. 58, toothed wheel 241 is constructed of a firstsection 241 a carrying the coupling elements of fixed configuration, andanother section 241 b carrying the coupling elements of a self-adaptiveconfiguration. The other toothed wheel 242 is similarly constructed of asection 242 a carrying the fixed-configuration coupling elements, andsection 242 b carrying the self-adaptive configuration couplingelements. As further shown in FIG. 58, section 241 a of wheel 241 isaligned with section 242 b of wheel 242, and section 241 b of wheel 241is aligned with section 242 a of wheel 242.

[0256] Since section 242 a of wheel 242 is constructed exactly the sameas section 241 a of wheel 241, and since section 241 b of wheel 241 isconstructed exactly the same as section 242 b of wheel 242, thedescription below will be restricted to that of section 241 a of wheel241 and section 242 b of wheel 241 engaged by section 241 a.

[0257] Both sections 241 a and 241 b of wheel 241 are formed with anannular array of radially-extending slots 243. As seen in wheel section242 b, that section (as well as section 241 b of wheel 241) receives aplurality of pins 244 each receiving an element defining a projection245 and an element defining a depression 246. As seen in wheel section241 a, that section (as well as section 242 a of wheel 242) receives aplurality of pivotal pins 247 defining the self-adaptive couplingelements which automatically adapt to the configuration of theprojections 245 and depressions 246 when engaged thereby.

[0258] It will thus be seen that, when the two toothed wheels 241, 242are disposed as illustrated in FIG. 58, with section 241 a of wheel 241meshing with section 242 b of wheel 242, and section 241 b of wheel 241meshing with section 242 a of wheel 242: (1) the radial positions ofboth coupling elements 244 and 247 will be changed to change theeffective diameter of the respective toothed wheel; (2) a change in theeffective diameter of one wheel will be accompanied by a correspondingchange in the effective diameter of the other wheel; and (3) pivotal pincoupling elements 247 in section 241 a of wheel 241 and in section 242 aof wheel 242 will self-adapt their configurations to the configurationsof the projections 245 and depressions 246 of sections 241 b of wheel241 and section 242 b of wheel 242 in all radial positions of theprojections and depressions, and thereby effect a non-slip coupling inall transmission ratios of the CVT system.

[0259]FIGS. 59a and 59 b schematically illustrate how a CVT system asillustrated in FIGS. 47-49 may be constructed as an infinitely variabletransmission (IVT) system, including the capability of zero velocity inits output shaft. Such a system may be called a planetary infinitelyvariable transmission (PIVT) system. FIGS. 59a and 59 b schematicallyillustrate two conditions of such a PIVT system.

[0260] The PIVT system schematically illustrated in FIGS. 59a and 59 b,and therein generally designated 250, includes a variable-diametertoothed wheel 251 having an annular array of pins (not shown)corresponding to pins 194 in FIGS. 47-49, which are radiallydisplaceable towards and away from the center axis 252 to enablechanging the effective diameter of the toothed wheel.

[0261] The transmission 250 also includes a planetary assembly,generally designated 253, which rotates around the teeth of the toothedwheel 251, namely the pins 194 of disc 191 shown in FIGS. 47-49.Planetary assembly 253 includes a first gear 254 meshing with the pins194, a second gear 255 fixed to gear 254 to rotate therewith, a thirdgear 256 meshing with gear 255, and a fourth gear 257 meshing with gear256. The planetary assembly 253 further includes a first arm 258rotatably mounting gears 254 and 255 at one end and gear 256 at theopposite end, and a second arm 259 pivotally mounted to the latter endof arm 258 and rotatably mounting gear 257 at its opposite end. Therotary axis of gear 257 is coaxial with the center axis 252 of thetoothed wheel 251.

[0262] Assume that toothed wheel 251 is fixed, and the planetaryassembly 253 rotates about the center axis 252 of the toothed wheel 251.If the input shaft is coupled to the planetary assembly 253, and theoutput shaft is coupled to the central axis 252 of the toothed wheel251, it will be seen that the transmission ratio between the input andoutput shafts can be changed by changing the effective diameter of thetoothed wheel 251. As described above with respect to FIGS. 47-49, orothers, the effective diameter of the toothed wheel 251 can be changedby displacing the pins 197 within the radial slots 193 of the disc 191,defining the toothed wheel 251 in FIGS. 59a and 59 b.

[0263]FIG. 59a illustrates one condition of the transmission, namelywherein the pins 194 (FIG. 47) are in their outermost position such thatthe effective diameter of the toothed wheel 251 is relatively large;whereas FIG. 59b schematically illustrates the condition wherein thepins 194 are in an inner position within their respective slots so thatthe effective diameter of the toothed wheel 251 is smaller.

[0264] Assume that the toothed wheel 251 is fixed against rotation,whereas all the other gears are free to rotate. Also assume that thetoothed wheel 251 has a diameter of 120 mm in the FIG. 59a condition and90 mm in the FIG. 59b condition, and that gear 254 has 40 teeth, gear255 has 10 teeth, gear 256 has 30 teeth, and gear 257 has 30 teeth.Actually, the size of gear 256 is of no consequence, since its role isonly to transfer the rotation from gear 255 to gear 257 in the oppositedirection.

[0265] It can be shown that in the condition illustrated in FIG. 59a,where the diameter ratio between gears 254 and 255 equals the diameterratio between the toothed wheel 251 and gear 257, that the output gear257 will not rotate; therefore, the output shaft 252 coupled to gear 257will have zero velocity.

[0266]FIG. 59b shows the condition wherein the diameter of the toothedwheel 251 has been reduced, e.g., from 120 mm to 90 mm. It can be shownthat this will change the transmission ratio from 1:0 of FIG. 59a to1:0.275 in FIG. 59b.

[0267] Thus when the drive shaft is connected to the toothed wheel 251,and the output shaft is connected to the internal gear 257, atransmission ratio of 1:1 is obtained in the condition of FIG. 59a, anda transmission ratio of 1:0.75 is obtained in the condition of FIG. 59b.

[0268] As shown below, the transmission ratio range can be furthermultiplied or divided by including a planetary gearing system whichenables the transmission ratio to be changed, e.g., from 1:1-1:0.75 to1:1-1:0.25.

[0269]FIG. 60 is an end view, and FIG. 61 is an exploded perspectiveview illustrating an implementation of the IVT system schematicallyillustrated in FIGS. 59a, 59 b. To facilitate understanding, thoseelements in FIGS. 60 and 61 which generally correspond to the elementsschematically illustrated in FIGS. 59a and 59 b are identified by thesame reference numerals.

[0270] Thus, variable-diameter toothed wheel 251 in the system 250 ofFIGS. 59a, 59 b, is constructed in a manner somewhat similar to thatdescribed above with respect to FIGS. 34-37, but modified to includeonly three slotted discs 251 a, 251 b, 251 c, receiving a plurality ofpins 251 d within the slots. Two of the discs 251 a, 251 c are formedwith straight radial slots, whereas the intermediate disc 251 b isformed with curved slots, so that the pins 251 d can be displacedradially inwardly or outwardly by effecting rotation between two outerdiscs 251 a, 251 c with respect to the middle disc 251 b.

[0271] Planetary assembly 253 includes the four gears 254, 255, 256 and257, as described with respect to FIGS. 59a, 59 b, except that gear 254which engages the pins 251 d is constituted of two toothed wheels 254 a,254 b (FIG. 61), e.g., similar to toothed wheel 20 a illustrated in FIG.10. Toothed wheels 254 a, 254 b contain the fixed projections anddepressions engaging the pins 251 d and causing the pins to self-adapttheir configurations to those of the projections on toothed wheels 254a, 254 b in all radial positions of the pins to thereby effect anon-slip coupling with the pins in all effective diameters of toothedwheel 251, as described earlier particularly with respect to FIG. 10.

[0272] As described above, rotation of gear 255 by gears 254 a, 254 b,rotates gear 256 which, in turn, rotates the central gear 257. Forpurposes of symmetry, the planetary gear assembly 253 preferablyincludes two sets of gears on the opposite sides of the toothed wheel251 and coupled to the central gear 257, as shown in FIG. 60.

[0273]FIG. 62 more particularly illustrates each of the pins 251 d inthe toothed wheel 251. As seen in FIG. 62, a mid-point of each pin 251 dis formed with a semi-circular bulge 251 e on one face aligned with asemi-circular recess 251 f on the opposite face. Recess 251 f isreceived within the curved slots of the intermediate ring 251 d, toallow each pin 251 d to pivot, as well as to be radially displaced,within the respective slot in order to change the effective diameter oftoothed wheel 251.

[0274]FIG. 61 illustrates the provision of an additional planetary gearassembly, generally designated 260, which may be used to enable divisionor multiplication of the transmission ratios. Planetary gear assembly260 includes an external ring 261, three planetary gears 262, a sun gear263 and a planet ring 264 rotatably mounting the three planetary gears262. With respect to the following three parts, external ring 261, sungear 263 and planet ring 264, one part is secured to one shaft, andanother part is secured to the other shaft. It will be seen that, insuch an arrangement, the output will be divided, or multiplied, by apredetermined number according to the relative dimensions of the gearsin the planetary gear assembly 260.

[0275] For example, assume that the transmission system 250 without theplanetary gear assembly 260 produces a transmission ratio ranging from1:1 up to 1:0.75. The planetary gear assembly 260 may be connected so asto divide the transmission ratio by a factor of 3, thereby increasingthe transmission ratio range from 1:1 to 1:0.25. To carry this out, forexample, the external ring 261 could have 60 teeth, the sun gear 263could have 30 teeth, and the planet gears 262 could each have 15 teeth.This will produce a ratio of 1:3 between the speed of rotation of thesun gear 263 and the speed of rotation of the planet ring 264, while theexternal ring 261 is static.

[0276] Thus, if the external ring 261 of the planetary transmission 260is connected to the original input shaft (e.g., the shaft of rotation ofthe toothed wheel 251), and the sun gear 263 of the planetarytransmission 260 is connected to the original output shaft (e.g., theshaft of the gear 257), the output produced on the output shaft will bedivided by the planetary transmission.

[0277] When the transmission is in a 1:1 state, the input shaft and theoutput shaft move together with the same speed. When the transmissionratio is reduced, the output shaft starts moving at a slower rate thanthe input shaft, and its speed is gradually reduced until it reaches themaximum speed which amounts to 75% of the speed of the input shaft.Therefore, the planetary transmission 260 will not have any effect whenthe ratio is 1:1, because then the original input shaft connected to theexternal ring 261, and the original output shaft connected to the sungear 263, move together at the same speed. Accordingly, the planet gears262 will also move at the same speed, and the planet ring 264 will alsomove at the same speed, such that the transmission ratio will remain1:1.

[0278] However, when the ratio starts to decrease from 1:1 in thedirection of 1:0.75, the planet gears 262 of the planetary transmission260 will move between the sun gear 263 and the external ring 261 at arate amounting to one-third of the speed of the original output shaftconnected to the sun gear 263, and thus reach a reduction of 0.25 whilethe original transmission has reduced its speed to 0.75, therebyproducing a transmission ratio ranging from 1:1 to 1:0.25 as desired.

[0279] It will be appreciated that the planetary transmission 260 couldalso be connected as to carry out multiplication instead of division.For example, if the connections are inverted, so that the new outputshaft is connected to the gear 263 of the planetary transmission 260,and the original output shaft is connected to the planet ring 264 of theplanetary transmission, the result will be multiplication by a factor of3, instead of division by the factor of 3.

[0280] The IVT system 250 illustrated in FIGS. 60 and 61 is particularlyuseful as a continuously variable transmission in a bicycle. Thetransmission ratios in bicycles between the front gear and the rear geargenerally range from about 1:1 at low gear up to about 4:1 at high gear.The PIVT system 250 illustrated in FIGS. 60 and 61 can be used toprovide an infinite number of gears as a substitute for the common21-gear system in bicycles. This can be done, for example, as follows:

[0281] The front gear and the chain may remain as in a standard bicycle.The chain will turn a rear gear at a constant ratio of 4:1, and thisgear will be affixed to the PIVT system of 60, 61 by means of aunilateral ratchet bearing drive, so that the transmission itself willmove together with the rear wheel of the bicycle, and the unilateralratchet bearing will only turn when the rider presses down on thepedals.

[0282] The rear system of a seven gear transmission may be replaced bythe PIVT system including the design as previously described, to producea transmission ratio ranging between 1:1 to 1:0.25. In such areplacement of the PIVT system, when the transmission ratio is 1:1theoriginal ratio of the gear wheels of 1:4 will be preserved; whereas whenthe transmission passes to a state of 1:0.25, the original ratio will bedivided by 4 to obtain a ratio of 1:1. The result will be a range oftransmission ratios ranging from 1:1 up to 4:1, as desired.

[0283] Another advantage in the system of FIGS. 60 and 61, as well as inthe below-described system of FIGS. 63 and 64 is that the drive shaftsand the driven shafts can be coaxial. In addition, since the pins 251 dare held between two discs, they can withstand large loads.

[0284]FIG. 63 illustrates a PIVT system, generally designated 270,similar to that described above but using a variable-diameter toothedwheel as an internal ring of variable diameter, instead of as anexternal ring of variable diameter. The advantage in such an approach isthat it enables a reduction in the number of pivotal pins in thevariable-diameter toothed wheel, and a corresponding reduction in thenumber of other parts. The principles previously described with respectto FIGS. 59a and 59 b, and FIGS. 60-62, remain the same, except that thetransmission ratio is determined according to the ratio between theexternal fixed-diameter ring 271, and the effective diameter of theinternal variable-diameter toothed wheel 272.

[0285] In this case, the toothed wheel 272, including its annular arrayof radially displaceable pins 273, is coupled to a pair offixed-diameter wheels 273, constructed as described above, to cause thepins 273 to assume a self-adaptive configuration to the projections anddepressions of the toothed wheels 274 in all effective diameters of thetoothed wheel 272. Toothed wheels 274 are coupled to smaller gears 275,which are meshed with planet gears 276, which planetate around the outerring 271. For purposes of symmetry, the illustrated system includesthree such planetary gear assemblies.

[0286] The variable-diameter toothed wheel 272, which serves as theinternal gear in the planetary assembly, may be constructed according toany of the constructions described above. FIG. 63 illustrates forpurposes of example, the construction of FIGS. 34-37, wherein theeffective diameter of the toothed wheel is varied by rotating itscurved-slot discs (111, 112, FIG. 34) with respect to its straight-slotdiscs (113, 114, FIG. 34) which radially displace the annular array ofcoupling pins 273 (116, FIG. 34). The variable-diameter toothed wheel272 is coupled, via the coupling pins 273, to a fixed-diameter toothedwheel 274 in a manner, such as described above, to cause the couplingpins to self-adapt themselves to the configuration of the projectionsand depressions on wheel 273 in all radial positions of the couplingpins, and thereby to provide a non-slip coupling with the coupling pinsin all effective diameters of the toothed wheel 272.

[0287] In this structure, a transmission 1:1 is attained when the ratiobetween the diameters of the external ring 271 and the internal toothedwheel 272 is identical to the ratio between wheel 274 and wheel 275. Ifthe external ring 271 is rotated, the internal toothed wheel 272 willrotate with it at a ratio of 1:1. Any change in the diameter of theinternal toothed wheel 272, by the annular displacement of its annulararray of pins 273, it will change this transmission ratio.

[0288] As in the case of the system illustrated in FIG. 61, anotherplanetary gear assembly may be provided (corresponding to assembly 260,FIG. 61) to further multiply or divide the transmission ratio in thesystem of FIG. 63.

[0289]FIG. 64 illustrates a PIVT system 280 including avariable-diameter toothed wheel according to the constructionillustrated in FIG. 52, and therefore identified by the same referencenumeral 220. It includes two conical discs 221, 222, mounting an annulararray of pin assemblies 223 which are radially movable to change theeffective diameter of the wheel by moving the two conical discs 221, 222towards or away from each other.

[0290] In the system illustrated in FIG. 64, the two conical discs 221,222 are moved towards and away from each other by one or two pivotallevers, shown at 281, 282. Thus, each lever may be coupled to a threadedpin 283, 284 having two reversed threads, such that when the lever ispivoted in one direction, the two discs 221, 222 are moved toward eachother; and when pivoted in the opposite direction, the discs are movedfurther apart. The two levers 281, 282 can be manually operated, or canbe automatically operated, e.g., in response to velocity as sensed byweights 285, 286, carried at the ends of the levers 281, 282.

[0291] The system illustrated in FIG. 64 further includes a gearassembly, generally designated 287, of the type described above withrespect to FIGS. 60 and 61, coupled to the annular array of pinassemblies 223 so as to effect a non-slip coupling therewith in alldiameters of the toothed wheel 220 in the same manner as describedabove.

[0292] As briefly described earlier, such an IVT system is particularlyuseful in bicycles. Thus, as the bicycle speed increases, thecentrifugal force applied to the weights 285, 286 will pivot the leverarms 281, 282 against the action of springs (not shown) to automaticallyincrease the transmission ratio of the system.

[0293] The invention has been described above with respect to manypreferred embodiments, but it will be appreciated that these are setforth merely for purposes of example, and that many other variations,may be made. For example, many of the transmissions described above foruse with two rotary members, could also be used wherein one of thetransmission members is a linearly-moveable member, such as a rack, asdescribed for example in FIG. 12. Also, many of the transmission systemsdescribed for driving a toothed wheel, could also be used for driving achain or belt, or vice versa. In addition, the various arrangements forradially displacing the coupling elements in order to change theeffective diameter of the toothed wheels could be used in other CVTsystems or in other applications.

[0294] It is appreciated that certain features of the invention, whichare, for clarity, described in the context of separate embodiments, mayalso be provided in combination in a single embodiment. Conversely,various features of the invention, which are, for brevity, described inthe context of a single embodiment, may also be provided separately orin any suitable subcombination.

[0295] Although the invention has been described in conjunction withspecific embodiments thereof, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

What is claimed is:
 1. A continuously-variable transmission, comprising:first and second transmission members each having a group of couplingelements successively engageable to couple the transmission members formovement together; at least one of said transmission members being arotary member rotatable about a rotary axis; at least one of said groupsof coupling elements being radially displaceable towards and away fromthe rotary axis to change the conversion ratio of said transmission; thecoupling elements of one of said groups on one of said transmissionmembers being of a fixed configuration defining an array of projectionseach of a fixed configuration alternating with depressions each of afixed configuration; said array of projections and depressions being ona surface of said one transmission member between opposite side faces ofsaid one transmission member, and having the same pitch for everycross-section of said surface perpendicular to the rotary axis; thecoupling elements of the other of said groups on the other of saidtransmission members being of a self-adaptive configuration, eachindividually movable in opposite directions to adapt itself to theconfiguration of said fixed configuration coupling elements in alldisplacement positions of the radially displaceable coupling elementsand to effect a non-slip coupling therewith in all said radialdisplacement positions.
 2. The transmission according to claim 1,wherein the projections and depressions of said fixed-configurationcoupling elements at one side face of said one transmission member arein a staggered relationship with respect to the projections anddepressions at the opposite side face of said one transmission member,such that each projection in one side face is aligned with a depressionin the opposite side face, along a line parallel to the rotary axis. 3.The transmission according to claim 2, wherein each of saidfixed-configuration coupling elements includes a gradual transition froma projection at one side face to a depression at the opposite side. 4.The transmission according to claim 2, wherein each of saidself-adaptive coupling elements is pivotally mounted to said onetransmission member such that when the coupling element is pivoted, oneend defines a projection engageable with a depression of thefixed-configuration coupling elements, and the opposite end defines adepression engaged by a projection of the fixed-configuration couplingelements.
 5. The transmission according to claim 2, wherein each of saidself-adaptive coupling elements includes a disc having a contact edgeand rotatable within a holder carried by said one transmission membersuch that when said disc is rotated, one end of said contact edgedefines a projection engageable with a depression of thefixed-configuration coupling elements, and the opposite end defines adepression engaged by a projection of the fixed-configuration couplingelements.
 6. The transmission according to claim 2, wherein each of saidfixed-configuration coupling elements includes a stepped transition froma projection ate one side face to a depression at the opposite sideface.
 7. The transmission according to claim 2, wherein each of saidself-adaptive coupling elements includes a pair of teeth on its oppositeends carried by said one transmission member and displaced together inopposite directions such that when the tooth at one end is displaced inone direction, it defines a projection engageable with a depression ofthe fixed-configuration coupling elements, and the tooth at the oppositeend is displaced in the opposite direction to define a depressionengageable by a projection of the fixed-configuration coupling elements.8. The transmission according to claim 7, wherein said teeth aremechanically actuated together by a rocking bar.
 9. The transmissionaccording to claim 2, wherein each of said self-adaptive couplingelements includes a shifting plate having teeth on its opposite ends anda space between said teeth, said shifting plate being shiftable within aholder carried by the respective transmission member such that when saidplate is shifted in one direction, it makes a tooth at one end effectiveto define a projection engageable with a depression in thefixed-configuration coupling elements, and the space between said teetheffective to define a depression engageable by a projection of thefixed-configuration coupling elements.
 10. The transmission according toclaim 1, wherein the projections and depressions of saidfixed-configuration coupling elements at one side face of said onetransmission member are in an aligned relation with respect to theprojections and depressions at the opposite side face of said onetransmission member; and each of said self-adaptive coupling elements onsaid other transmission member includes two end sections which areoffset from each other a distance equal to one-half said pitch to enablesaid self-adaptive coupling elements to automatically adapt themselvesto the configuration of said fixed-configuration coupling elements suchas to effect a non-slip coupling therewith in all effective diameters ofsaid rotary member.
 11. The transmission according to claim 1, whereinthe projections and depressions of said fixed-configuration couplingelements at one side face of said one transmission member are in analigned relation with respect to the projections and depressions at theopposite side face of said one transmission member; and each of saidself-adaptive coupling elements includes a pivotal assembly on saidother transmission member pivotal about an axis perpendicular to thedirection of movement of the one transmission member; each of saidpivotal assemblies having a pair of spaced arms adapted to engage spacedpoints on the projections and depressions of said one transmissionmember, to thereby permit said self-adaptive coupling elements toautomatically adapt themselves to the configuration of saidfixed-configuration coupling elements such as to effect a non-slipcoupling therewith in all effective diameters of said rotary member. 12.The transmission according to claim 1, wherein the projections anddepressions of said fixed-configuration coupling elements at one sideface of said one transmission member are in an aligned relation withrespect to the projections and depressions at the opposite side face ofsaid one transmission member; and each of said self-adaptive couplingelements includes a pivotal assembly on said other transmission memberpivotal about an axis perpendicular to the direction of movement of theone transmission member; each of said pivotal assemblies having a pairof spaced teeth adapted to engage spaced points on the projections anddepressions of said one transmission member, to thereby permit saidself-adaptive coupling elements to automatically adapt themselves to theconfiguration of said fixed-configuration coupling elements such as toeffect a non-slip coupling therewith in all effective diameters of saidrotary member.
 13. The transmission according to claim 1, wherein saidrotary member is a variable-diameter toothed wheel carrying saidself-adaptive coupling elements in a radially-displaceable mannerthereon; and said other transmission member is a fixed-diameter toothedwheel carrying said fixed-configuration coupling elements.
 14. Thetransmission according to claim 1, wherein said rotary member is avariable-diameter toothed wheel carrying said self-adaptive couplingelements in a radially-displaceable manner thereon; and said othertransmission member is a toothed rack carrying said fixed-configurationcoupling elements.
 15. The transmission according to claim 1, whereinsaid rotary member is a variable-diameter toothed wheel carrying saidself-adaptive coupling elements in a radially-displaceable mannerthereon; and said other transmission member is a flexible chain carryingsaid fixed-configuration coupling elements.
 16. The transmissionaccording to claim 1, wherein said rotary member is a variable-diametertoothed wheel carrying said self-adaptive coupling elements in aradially-displaceable manner thereon; and said other transmission memberis a flexible belt carrying said fixed-configuration coupling elements.17. The transmission according to claim 1, wherein said othertransmission member carries said self-adaptive coupling elements in aradially-displaceable manner; and said rotary member carries saidfixed-configuration coupling elements.
 18. The transmission according toclaim 17, wherein said other transmission member includes a disc formedwith an annular array of radial slots around a central axis; and saidself-adaptive coupling elements include an annular array of pinsdisplaceable within said slots towards and away from said central axis.19. The transmission according to claim 18, wherein said rotary memberincludes a gear assembly having at least one gear meshing with saidannular array of pins such that the gear assembly rotates around saidcentral axis of said disc.
 20. The transmission according to claim 19,wherein said disc is movable with respect to said gear assembly tochange the radial distance of the gear assembly from said central axisof the disc, and thereby to change the transmission ratio of saidtransmission.
 21. The transmission according to claim 19, wherein saidgear assembly is movable with respect to said disc to change the radialdistance of the gear assembly from said central axis of the disc, andthereby to change the transmission ratio of said transmission.
 22. Thetransmission according to claim 1, wherein said rotary member carriessaid fixed-configuration coupling elements in a radially-displaceablemanner; and said other transmission member carries said self-adaptivecoupling elements in an individually displaceable manner to adaptthemselves to the configuration of said fixed-configuration couplingelements in all displacement positions thereof.
 23. The transmissionaccording to claim 22, wherein said rotary member is formed with anannular array of radial slots around its rotational axis and includes anannular array of pins radially displaceable within said slots andcarrying said fixed configuration coupling elements.
 24. Thetransmission according to claim 23, wherein said self-adaptive couplingelements carried by said other transmission member are pins pivotallymounted to said other transmission member.
 25. The transmissionaccording to claim 24, wherein said other transmission member is asecond rotary member.
 26. The transmission according to claim 25,wherein said second rotary member is a flexible chain or belt carryingsaid pivotally-mounted pins on its inner surface.
 27. The transmissionaccording to claim 25, wherein said second rotary member is afixed-diameter toothed wheel and carries said pivotally-mounted pins inthe form of an annular array around its outer periphery.
 28. Thetransmission according to claim 27, wherein both of said transmissionmembers are rotary members; each of said rotary members including afirst section carrying said self-adaptive coupling elements, and asecond section carrying said fixed-configuration coupling elements; thecoupling elements of one of said sections being radially displaceable asa group towards and away from the rotary axis to change the conversionratio of said transmission; the two sections of each rotary member beingin side-by-side relation, and the two rotary members being oriented withrespect to each other such that the first section of one rotary memberis aligned with and engaged by the second section of the other rotarymember, and vice versa.
 29. The transmission according to claim 1,wherein said first and second transmission members are first and secondrotary members, respectively; said first rotary member being a variablediameter toothed wheel and including said radially-displaceable couplingelements; said second rotary member being a fixed-diameter toothedwheel.
 30. The transmission according to claim 29, wherein saidradially-displaceable coupling elements on said variable-diametertoothed wheel are of said self-adaptive configuration; and said couplingelements on said fixed-diameter toothed wheel are of said fixedconfiguration.
 31. The transmission according to claim 29, wherein thereare a plurality of said variable-diameter toothed wheels fixed to eachother to rotate together, and a plurality of said fixed-diameter toothedwheels fixed to each other, such as to enable extending the range oftransmission ratios without undue clearances between said projectionsand depressions, and/or sharing the load.
 32. The transmission accordingto claim 29, wherein said fixed-diameter toothed wheel is mounted at oneend of an arm urging the latter toothed wheel into engagement with thecoupling elements of said variable-diameter toothed wheel; said armbeing pivotal about an axis rotatably mounting a second fixed-diametertoothed wheel meshing with said first mentioned fixed-diameter toothedwheel such that the pivotal axis of said arm serves as the rotary axisof said second fixed-diameter toothed wheel, which rotary axis remainsat a fixed location with respect to the rotary axis of said variablediameter toothed wheel for all transmission ratios of the transmission.33. The transmission according to claim 1, wherein said rotary memberincludes a pair of conical discs each formed with an annular array ofradial slots; said radially-displaceable coupling elements beingdisposed in an annular array between said discs and having theiropposite ends slidably received in said slots, such that moving thediscs towards or away from each other radially displaces said lattercoupling elements to change the effective diameter of the rotary member.34. The transmission according to claim 1, wherein said rotary memberincludes: a first member in the form of a disc having an annular arrayof radial slots radiating from the rotary axis of the rotary member; anda second member carrying an annular array of triangular plates havinginclined edges received in said radial slots and movable therein; saidradially-displaceable coupling elements being disposed in an annulararray between said radial slots and triangular plates such that movingsaid first and second members towards or away from each other radiallydisplaces said annular array of coupling elements to change theeffective diameter of the rotary member.
 35. The transmission accordingto claim 34, wherein said second member carrying said triangular platesis a second disc movable towards and away from said disc having theradial slots.
 36. The transmission according to claim 34, wherein saidsecond member carrying said triangular plates includes a bearing memberslideably received on the rotary axis of the rotary member.
 37. Thetransmission according to claim 34, wherein each of saidradially-displaceable coupling elements has one end slidably received ina radial slot of said disc, and an opposite end slidably receiving theinclined edge of one of said triangular plates.
 38. The transmissionaccording to claim 1, wherein said rotary member is in the shape of acone having a small diameter inner end rotatably mounted on the rotaryaxis, and a large diameter outer end, said cone being formed with aplurality of radial slots extending between said outer end and saidinner end; said radially-displaceable coupling elements being movable insaid slots to change the effective diameter of said rotary member. 39.The transmission according to claim 1, wherein said rotary memberincludes a disc formed with a plurality of radially-extending slotsreceiving said radially-displaceable coupling elements, and said othertransmission member includes a pair of toothed wheels straddling saiddisc and engageable with the opposite ends of said latter couplingelements.
 40. The transmission according to claim 1, wherein each ofsaid radially-displaceable coupling elements, is spring urged towardsthe rotary axis of the rotary member.
 41. The transmission according toclaim 1, wherein said rotary member includes at least a first discformed with an annular array of radial straight slots, and a second discformed with an annular array of radial curved slots; saidradially-displaceable coupling elements being disposed in said slotssuch that rotating one disc with respect to the other radially displacessaid coupling elements to change the effective diameter of the rotarymember.
 42. The transmission according to claim 41, wherein said rotarymember includes a pair of said first and second discs on each of theopposite ends of said coupling elements.
 43. The transmission accordingto claim 41, wherein each of said annular array of radially-displaceablecoupling elements is of said self-adaptive configuration and includes apin received in said slots, and a contact element pivotally mounted tosaid pin.
 44. The transmission according to claim 1, wherein: said othertransmission member includes a disc formed with an annular array ofradial slots; said self-adaptive coupling elements include an annulararray of pins displaceable within said slots; and said rotary memberincludes a gear assembly having a gear meshing with said annular arrayof pins for rotating the gear assembly about the center of said annulararray.
 45. The transmission according to claim 44, wherein said disc andsaid annular array of pins are also rotatable about the rotary axis. 46.The transmission according to claim 44, wherein said gear assembly ismovable radially with respect to said disc to radially displace the pinsin their respective slots, and thereby to change the transmission ratio.47. The transmission according to claim 44, wherein said disc is movableradially with respect to said gear assembly to radially displace thepins in their respective slots and thereby to change the transmissionratio.
 48. The transmission according to claim 44, wherein said gearassembly includes a pair of gears on each of the two diametricallyopposite sides of said disc, and said disc is movable towards one pairof gears and away from the other pair of gears to radially displace thepins within said slots of the disc, and thereby to change thetransmission ratio.
 49. The transmission according to claim 44, whereinthe transmission includes a second disc having an annular array of pins,and said gear assembly includes a third gear in axial alignment withsaid pair of gears such that said pair of gears straddle, and mesh with,the annular array of pins of one of said discs; while said third gearand one of said pair of gears straddle and mesh with the annular arrayof pins of said second disc.
 50. The transmission according to claim 44,wherein said gear assembly includes two pairs of said gears straddlingthe opposite sides of said disc, the gears of each pair meshing withends of the pins projecting through the respective side of the disc. 51.The transmission according to claim 44, wherein: said gear assemblyincludes a roller on one side of the annular array of pins, and a pairof gears meshing with the opposite side of said annular array of pinsfor rotating the gear assembly about the center of said annular array ofpins.
 52. The transmission according to claim 44, wherein said othertransmission member includes a pair of said discs axially-spaced fromeach other and formed with an annular array of radial slots displaceablysupporting said annular array of pins between said pair of discs; saiddiscs being movable with respect to each other to radially displace saidpins, and thereby to change the effective radius of rotation of saidgear assembly.
 53. The transmission according to claim 52, wherein saiddiscs are movable towards and away from each other and have conicalsurfaces displaceably supporting said annular array of pins.
 54. Thetransmission according to claim 53, wherein said pins have rollersrollable along said conical surfaces for radially displacing said pins.55. The transmission according to claim 1, wherein both of saidtransmission members are rotary members, one of said rotary memberscarrying on its outer periphery said self-adaptive coupling elements inthe form of an annular array of axially-extending pins each pivotal atan intermediate location thereof to enable them to assume saidself-adaptive configuration; the other of said rotary members carryingon its outer periphery said fixed-configuration coupling elements in theform of an annular array of axially-extending pins carrying said fixedconfiguration projections and depressions.
 56. The transmissionaccording to claim 55, wherein said pins carrying saidfixed-configuration coupling elements are radially displaceable tochange the effective diameter of said other rotary member.
 57. Thetransmission according to claim 55, wherein each of said pins carryingsaid fixed-configuration coupling elements includes an element defininga projection, and another element defining a depression spaced from saidelement defining a projection.
 58. The transmission according to claim57, wherein said pins carrying said fixed-configuration couplingelements are arranged in two alternating series, the pins in one seriesincluding the projections and depressions at its opposite ends, the pinsin the other series including the projections and depressions in amid-portion of the respective pin.
 59. The transmission according toclaim 58, wherein the pins defining said self-adaptive coupling elementsin said one rotary member are also arranged in two alternating series ofshort pins alternating with longer pins.
 60. The transmission accordingto claim 55, wherein one of said rotary members is a variable-diametertoothed wheel, and the other of said rotary members is a fixed-diametertoothed wheel.
 61. The transmission according to claim 55, wherein oneof said rotary members is a variable-diameter toothed wheel, and theother of said rotary members is a closed-loop coupling member.
 62. Thetransmission according to claim 55, wherein each of said rotary membersincludes two sections in side-by-side relation; a first section of eachof said rotary members including the pins of said self-adaptive couplingelements, and a second section of each of said rotary members includingthe pins of said fixed-configuration coupling elements; said rotarymembers being oriented such that said first section of one rotary memberis aligned with and engaged by said second section of the other rotarymember, and vice versa.
 63. The transmission according to claim 1,wherein both of said transmission members are rotary members; each ofsaid rotary members including a first section carrying saidself-adaptive coupling elements, and a second section carrying saidfixed-configuration coupling elements; the coupling elements of one ofsaid sections being radially displaceable as a group towards and awayfrom the rotary axis to change the conversion ratio of saidtransmission; the two sections of each rotary member being inside-by-side relation, and the two rotary members being oriented withrespect to each other such that the first section of one rotary memberis aligned with and engaged by the second section of the other rotarymember, and vice versa.
 64. The transmission according to claim 63,wherein said fixed-configuration coupling elements are radiallydisplaceable in its respective rotary member.
 65. The transmissionaccording to claim 1, wherein said other transmission member is a chaincoupling said rotary member to a sprocket wheel, said transmissionfurther including a pinion spring-urged against said chain to maintaintautness in said chain.
 66. The transmission according to claim 1,wherein said other transmission member is a flexible closed loopcoupling said rotary member to another rotary member of likeconstruction such that an increase in the diameter of one rotary memberis accompanied by a decrease in diameter of the other rotary member tomaintain tautness in said flexible closed loop.
 67. The transmissionaccording to claim 66, wherein the two rotary members are controlled bya control mechanism which produces a concurrent increase in diameter ofsaid one rotary member and decrease in diameter of said other rotarymember to maintain the tautness in said flexible closed loop coupling.68. The transmission according to claim 67, wherein said controlmechanism includes a pivotal arm coupled at one side to one rotarymember to increase its effective diameter and at the opposite side tothe other rotary member to decrease its effective diameter.
 69. Thetransmission according to claim 67, wherein said control mechanismincludes a threaded member coupled to each of said rotary members; saidthreaded members being coupled together and to their respective rotarymember to effect concurrent changes in effective diameter of the tworotary members by the same amounts but in opposite direction.
 70. Thetransmission according to claim 67, wherein one rotary member is coupledto a first gear, and the other rotary member is coupled to a second gearmeshing with said first gear; said transmission further including adifferential mechanism between said gears effective to enable the rangeof transmission ratios between said rotary members to be controlled toproduce a zero velocity output.
 71. The transmission according to claim1, wherein said rotary member includes an inner pair of spaced discsjoined together by a first ring, and an outer pair of spaced discsjoined together by a second ring coaxial with said first ring; one pairof discs being formed with a plurality of radially-extending straightslots, and the other pair of discs being formed with a plurality ofradially-extending curved slots; the opposite ends of each of said ofcoupling elements of said rotary member being received in both astraight slot and in a curved slot of the respective discs such thatrotation of one of said discs in each pair with respect to the otherdisc in the pair causes said coupling elements to move radially withrespect to said discs, according to the direction of rotation, therebychanging the effective diameter of the rotary member.
 72. Thetransmission according to claim 71, wherein one disc of each pair iscoupled to the other disc of the respective pair by a differential gearassembly which is controllable to effect an angular displacement of thetwo discs, and thereby to change the effective diameter of said rotarymember while the transmission is operating.
 73. The transmissionaccording to claim 1, wherein said other transmission member is avariable-diameter toothed wheel having an annular series of saidself-adaptive coupling elements radially displaceable towards and awayfrom the axis of the toothed wheel; and said rotary member is a gearassembly meshing with said toothed wheel to rotate around the centralaxis of said toothed wheel.
 74. The transmission according to claim 73,wherein said gear assembly is located and rotates within said toothedwheel.
 75. The transmission according to claim 73, wherein said gearassembly is located outwardly of and rotates around said toothed wheel.76. The transmission according to claim 1, wherein said couplingelements of said rotary member are provided with resilient pads tocushion their contact with the coupling elements of said othertransmission member.
 77. The transmission according to claim 1, whereinsaid coupling elements of said other transmission member are providedwith resilient pads to cushion their contact with the coupling elementsof said rotary member.
 78. The transmission according to claim 1,wherein the transmission further includes a condition sensor for sensinga predetermined condition, and an automatic control system forautomatically displacing said radially-displaceable coupling elements tochange the radial distance of said rotary member from the rotary axis,and thereby the transmission ratio of said continuously-variabletransmission, in response to said sensed condition.
 79. The transmissionaccording to claim 78, wherein said condition sensor senses velocity ofthe transmission and automatically controls said transmission ratio inresponse thereto.
 80. The transmission according to claim 78, whereinsaid condition sensor senses load on the transmission, and automaticallycontrols said transmission ratio in response thereto.
 81. Thetransmission according to claim 78, wherein the transmission is includedin a vehicle having an engine for driving the vehicle, said conditionsensor sensing the load on said engine and automatically controllingsaid transmission ratio in response thereto.
 82. The transmissionaccording to claim 78, wherein said automatic control system includes aresponse selector for selecting one of at least two predeterminedresponses of the automatic control of the transmission ratio of thecontinuously-variable transmission to the predetermined sensedcondition.
 83. A continuously-variable transmission, comprising: firstand second transmission members each having a group of coupling elementssuccessively engageable to couple the transmission members for movementtogether; at least one of said transmission members being a rotarymember rotatable about a rotary axis; at least one of said groups ofcoupling elements being radially displaceable towards and away from therotary axis the rotary axis to change the conversion ratio of saidtransmission; the coupling elements of one of said groups being of afixed configuration defining projections alternating with depressionseach of a fixed configuration; the coupling elements of the other ofsaid groups being of a self-adaptive configuration, each individuallymovable in opposite directions to adapt itself to the configuration ofsaid fixed configuration coupling elemenrs, in all displacementpositions of the radially displaceable coupling elements; said othertransmission member including a disc formed with an annular array ofradial slots; said self-adaptive coupling elements including an annulararray of pins displaceable within said slots; and said rotary memberincluding a gear assembly having a gear meshing with said annular arrayof pins for producing a non-slip coupling therewith while effectingrelative rotation between said disc and said gear assembly about thecenter of said annular array.
 84. The transmission according to claim83, wherein said disc and said annular array of pins are also rotatableabout the rotary axis.
 85. The transmission according to claim 83,wherein said gear assembly is movable radially with respect to said discto radially displace the pins in their respective slots, and thereby tochange the transmission ratio.
 86. The transmission according to claim83, wherein said disc is movable radially with respect to said gearassembly to radially displace the pins in their respective slots andthereby to change the transmission ratio.
 87. The transmission accordingto claim 83, wherein said gear assembly includes a pair of gears on eachof the two diametrically opposite sides of said disc, and said disc ismovable towards one pair of gears and away from the other pair of gearsto radially displace the pins within said slots of the disc, and therebyto change the transmission ratio.
 88. The transmission according toclaim 83, wherein the transmission includes a second disc having anannular array of pins, and said gear assembly includes a third gear inaxial alignment with said pair of gears such that said pair of gearsstraddle, and mesh with, the annular array of pins of one of said discs;while said third gear and one of said pair of gears straddle and meshwith the annular array of pins of said second disc.
 89. The transmissionaccording to claim 83, wherein said gear assembly includes two pairs ofsaid gears straddling the opposite sides of said disc, the gears of eachpair meshing with ends of the pins projecting through the respectiveside of the disc.
 90. The transmission according to claim 83, wherein:said gear assembly includes a roller on one side of the annular array ofpins, and a pair of gears meshing with the opposite side of said annulararray of pins for rotating the gear assembly about the center of saidannular array of pins.
 91. The transmission according to claim 83,wherein said other transmission member includes a pair of said discsaxially-spaced from each other and formed with an annular array ofradial slots displaceably supporting said annular array of pins betweensaid pair of discs; said discs being movable with respect to each otherto radially displace said pins, and thereby to change the effectiveradius of rotation of said gear assembly.
 92. The transmission accordingto claim 91, wherein said discs are movable towards and away from eachother and have conical surfaces displaceably supporting said annulararray of pins.
 93. The transmission according to claim 92, wherein saidpins have rollers rollable along said conical surfaces for radiallydisplacing said pins.
 94. The transmission according to claim 83,wherein both of said transmission members are rotary members, one ofsaid rotary members carrying on its outer periphery said self-adaptivecoupling elements in the form of an annular array of axially-extendingpins each pivotal at an intermediate location thereof to enable them toassume said self-adaptive configuration; the other of said rotarymembers carrying on its outer periphery said fixed-configurationcoupling elements in the form of an annular array of axially-extendingpins carrying said fixed configuration projections and depressions. 95.The transmission according to claim 94, wherein said pins carrying saidfixed-configuration coupling elements are radially displaceable tochange the effective diameter of said other rotary member.
 96. Thetransmission according to claim 94, wherein each of said pins carryingsaid fixed-configuration coupling elements includes an element defininga projection, and another element defining a depression spaced from saidelement defining a projection.
 97. The transmission according to claim96, wherein said pins carrying said fixed-configuration couplingelements are arranged in two alternating series, the pins in one seriesincluding the projections and depressions at its opposite ends, the pinsin the other series including the projections and depressions in amid-portion of the respective pin.
 98. The transmission according toclaim 94, wherein the pins defining said self-adaptive coupling elementsin said one rotary member are also arranged in two alternating series ofshort pins alternating with longer pins.
 99. The transmission accordingto claim 94, wherein one of said rotary members is a variable-diametertoothed wheel, and the other of said rotary members is a fixed-diametertoothed wheel.
 100. The transmission according to claim 94, wherein oneof said rotary members is a variable-diameter toothed wheel, and theother of said rotary members is a closed-loop coupling member.
 101. Thetransmission according to claim 94, wherein each of said rotary membersincludes two sections in side-by-side relation; a first section of eachof said rotary members including the pins of said self-adaptive couplingelements, and a second section of each of said rotary members includingthe pins of said fixed-configuration coupling elements; said rotarymembers being oriented such that said first section of one rotary memberis aligned with and engaged by said second section of the other rotarymember, and vice versa.
 102. A continuously-variable transmission,comprising: first and second transmission members each having a group ofcoupling elements successively engageable to couple the transmissionmembers for movement together; at least one of said transmission membersbeing a rotary member rotatable about a rotary axis; at least one ofsaid groups of coupling elements being radially displaceable towards andaway from the rotary axis the rotary axis to change the conversion ratioof said transmission; the coupling elements of one of said groups beingof a fixed configuration defining projections alternating withdepressions each of a fixed configuration; the coupling elements of theother of said groups being of a self-adaptive configuration, eachindividually movable in opposite directions to adapt itself to theconfiguration of said fixed configuration coupling elements in alldisplacement positions of the radially-displaceable coupling elements;said rotary member including an inner pair of spaced discs joinedtogether by a first ring, and an outer pair of spaced discs joinedtogether by a second ring coaxial with said first ring; one pair ofdiscs being formed with a plurality of radially-extending straightslots, and the other pair of discs being formed with a plurality ofradially-extending curved slots; the opposite ends of each of said ofcoupling elements of said rotary member being received in both astraight slot and in a curved slot of the respective discs such thatrotation of one of said discs in each pair with respect to the otherdisc in the pair causes said coupling elements to move radially withrespect to said discs, according to the direction of rotation, therebychanging the effective diameter of the rotary member.
 103. Thetransmission according to claim 102, wherein one disc of each pair iscoupled to the other disc of the respective pair by a differential gearassembly which is controllable to effect an angular displacement of thetwo discs, and thereby to change the effective diameter of said rotarymember while the transmission is operating.
 104. A continuously-variabletransmission, comprising: first and second rotary transmission memberseach having a group of coupling elements successively engageable tocouple the transmission members for movement together; at least one ofsaid groups of coupling elements being radially displaceable towards andaway from the rotary axis to change the conversion ratio of saidtransmission; the coupling elements of one of said groups being of afixed configuration defining projections alternating with depressionseach of a fixed configuration; the coupling elements of the other ofsaid groups being of a self-adaptive configuration, each individuallymovable in opposite directions to adapt itself to the configuration ofsaid fixed-configuration coupling elements in all displacement positionsof the radially-displaceable coupling elements; one of said rotarytransmission member being a variable-diameter toothed wheel having anannular series of said self-adaptive coupling elements radiallydisplaceable towards and away from the axis of the toothed wheel; theother of said rotary transmission member being a gear assembly meshingwith said toothed wheel to rotate around the central axis of saidtoothed wheel.
 105. The transmission according to claim 104, whereinsaid gear assembly is located within and rotates within said toothedwheel.
 106. The transmission according to claim 104, wherein said gearassembly is located outwardly of and rotates around said toothed wheel.107. A transmission for transmitting mechanical motion in apredetermined direction between a first member and a second member; saidfirst member including a coupling element; said second member having anengagement surface formed with a topography of projections anddepressions in a periodic pattern of the same pitch in everycross-section parallel to the direction of motion; said coupling elementof said first member being placeable on said engagement surface of saidsecond member at any point along said direction of motion and resting onsaid surface along at least one line of contact defined by points ofrest; said coupling element of said first member having at least onepoint that does not change its elevation above said second member forany of said points of rest; said line of contact resting at leastpartially on a positive slope and partially on a negative slope of saidengagement surface.
 108. The transmission according to claim 107,wherein at least one of said members is a rotary member, and saidpredetermined direction is the rotary direction of rotation of the axisabout which said rotary member rotates.
 109. The transmission accordingto claim 108, wherein said first member is a variable diameter rotarymember including an annular array of said coupling elements radiallydisplaceable to change its effective diameter, and thereby to enablesaid transmission to continuously-vary the transmission ratio betweensaid first and second members.
 110. A transmission for transmittingmechanical motion between a rotary driving member and a rotary drivenmember having parallel axes of rotation, comprising: a pin parallel tothe axes of rotation of said driving and driven members; one of saidmembers being engageable with said pin allowing it a relative movementonly in a direction that is essentially perpendicular to said axes ofrotation and perpendicular to the pin; the other of said members beingengageable with said pin such that when said other member is rotated, itforces the pin to move in both the tangential and the radial directions,wherein the tangential movement is in the direction of said motion, andthe radial movement is periodic around a median radius.
 111. Atransmission according to claim 110, including a mechanism that changesthe distance between said axes of rotation of said first and secondmembers.
 112. A variable-diameter rotary wheel, comprising: an innerpair of spaced discs joined together by a first ring, and an outer pairof spaced discs joined together by a second ring coaxial with said firstring; one pair of discs being formed with a plurality ofradially-extending straight slots, and the other pair of discs beingformed with a plurality of radially-extending curved slots; and aplurality of pins having their opposite ends received in both a straightslot and in a curved slot of the respective discs such that rotation ofone of said discs in each pair with respect to the other disc in thepair causes said pins to move radially with respect to said discs,according to the direction of rotation, thereby changing the effectivediameter of the rotary member.
 113. The variable-diameter rotary wheelaccording to claim 112, wherein each of said of plurality of pinspivotally mounts a coupling element for coupling the variable-diameterrotary wheel to a transmission member.
 114. The variable-diameter rotarywheel according to claim 112, wherein one disc of each pair is coupledto the other disc of the respective pair by a differential gear assemblywhich is controllable to effect an angular displacement of the twodiscs, and thereby to change the effective diameter of said wheel. 115.A variable-diameter rotary wheel, comprising: a cone having a smalldiameter inner end and a large diameter outer end; said cone beingformed with a plurality of slots extending between said outer end andsaid inner end; and a plurality of coupling elements for coupling thecone to a transmission member, said coupling elements being movable insaid slots to change the effective diameter of said wheel.
 116. Avariable-diameter rotary wheel, comprising: a disc formed with aplurality of radially-extending slots; and an annular array of pinsradially displaceable within said slots; each of said pins pivotallymounting a coupling element for coupling the variable-diameter rotarywheel to a transmission member.
 117. A variable-diameter rotary wheel,comprising: a pair of axially-spaced discs; one of said discs beingformed with an annular array of radial straight slots, and the other ofsaid discs being formed with an annular array of radial curved slots;and a plurality of pins received in said slots and displaceable radiallytherein by rotating one of said discs with respect to the other tochange the effective diameter of said wheel.
 118. A rotary member forcoupling to another like rotary member, comprising: a plurality ofaxially-extending, radially displaceable coupling elements on a firstsection of the rotary member defining projections and depressions offixed configuration; and a plurality of axially-extending pivotalcoupling elements on a second section of the rotary member definingprojections and depressions of a self-adapting configuration.
 119. Therotary member according to claim 118, wherein said radially-displaceablecoupling elements are carried by pins displaceable within radial slotsformed in the rotary member, and said pivotal coupling elements are aform of pins pivotally mounted at intermediate locations thereof to theouter periphery of the rotary member.
 120. A transmission member forcoupling to a rotary member rotatable about a rotary axis; saidtransmission member having opposite side faces and a surface betweensaid side faces formed with an array of projections and depressions forcoupling to another transmission member; said array of projections anddepressions having the same peach for every cross section of saidsurface perpendicular to said rotary axis, being of the same pitch fromone side face to the opposite side face; the projections and depressionsin one side face being in a staggered relation to the projections anddepressions in the opposite side face, such that each projection in oneside face is aligned with a depression in the opposite side face along aline parallel to the rotary axis.
 121. The transmission member accordingto claim 120, wherein the transmission member is a toothed wheel. 122.The toothed wheel according to claim 121, wherein each of saidprojections and depressions includes a gradual transition from aprojection at one side face of the toothed wheel to a depression at theopposite side face of the toothed wheel.
 123. The toothed wheelaccording to claim 121, wherein each of said projections and depressionsincludes a stepped transition from a projection at one side face of thetoothed wheel to a depression at the opposite side face of the toothedwheel.
 124. The transmission member according to claim 120, wherein saidtransmission member is a closed-loop flexible chain.
 125. The flexiblechain according to claim 124, wherein each of said projections anddepressions includes a gradual transition from a projection at one sideface of the toothed wheel to a depression at the opposite side face ofthe toothed wheel.
 126. The flexible chain according to claim 124,wherein each of said projections and depressions includes a steppedtransition from a projection at one side face of the toothed wheel to adepression at the opposite side face of the toothed wheel.
 127. Thetransmission member according to claim 120, wherein said transmissionmember is a closed-loop flexible belt.
 128. The flexible belt accordingto claim 127, wherein each of said projections and depressions includesa gradual transition from a projection at one side face of the toothedwheel to a depression at the opposite side face of the toothed wheel.129. The flexible belt according to claim 127, wherein each of saidprojections and depressions includes a stepped transition from aprojection at one side face of the toothed wheel to a depression at theopposite side face of the toothed wheel.
 130. The transmission memberaccording to claim 120, wherein said transmission member is a rack. 131.The rack according to claim 130, wherein each of said projections anddepressions includes a gradual transition from a projection at one sideface of the toothed wheel to a depression at the opposite side face ofthe toothed wheel.
 132. The rack according to claim 130, wherein each ofsaid projections and depressions includes a stepped transition from aprojection at one side face of the toothed wheel to a depression at theopposite side face of the toothed wheel.